WRZM243

It depends.  If you mount them on the same mast with one vertically above the other they can be just a 14 inches (a half wavelength) or so apart.  If you place them on the same level then the transmissions from one antenna are much more likely to affect the other.  The signal strength goes down by 10 db (a factor of 10) for every foot of horizontal separation.
A foot of vertical separation is worth about ten feet of horizontal separation.

If the repeater is or has been active, it must be identified at least once every 15 minutes. If it is just listening and not transmitting, it does not have to be identified. Read through the rules for GMRS in Part 95 of the FCC regulations.

I have only 1 repeater near me that Id’s and it does it every 4min.  It’s stupid and annoying and gets in the way of the channel use.  
 
Depends on how it’s used   Normally just like a station every 15m and at the end of transmission, however …..
 
(c) Any GMRS repeater station is not required to transmit station identification if:
(1) It retransmits only communications from GMRS stations operating under authority of the individual license under which it operates; and,
(2) The GMRS stations whose communications are retransmitted are properly identified in accordance with this section.

You probably doomed yourself and your loved ones by placing an artificial and unrealistic constraint on your communications when you adopted the constraint that “the only source of communications is GMRS”.
Like the others, I don’t understand why you’re packing around a repeater.  
What your scenario is missing is realistic planning.  Instead of deliberately constraining yourself to GMRS you should ask what communications could help you in such a disaster.  You should have a plan set up in advance that include near and distance communications, at least the ability to listen to outside communications to discover the nature and size of the disaster. You should at the very least be prepared to receive news via broadcast and shortwave radio.  That means knowing where to tune and when. A huge step up from that would be the ability to respond on a variety of frequencies.
Ideally, the communications gear you choose uses very low power while listening and capable of listening across a very wide range of frequencies. An example of a poor choice would be my FTDX10 ham radio transceiver.  Yeah, it’s 100 watts output, but when receiving it uses amps.  A better choice would be the Icom IC-705.  Its receiver is plenty good and capable of receiving most frequencies from broadcast AM up to 470 MHz and all modes, so capable of receiving GMRS and its current consumption is only a fraction of that of my full size transceiver.  With the right antenna you can listen to stations that are thousands of miles away.  I don’t know if a MARS/CAP mod on the IC-705 allows it to transmit on the GMRS channels in an emergency, but honestly, GMRS is very limited as a true emergency band.  Don’t get me wrong, having a bunch of people who have GMRS radios is infinitely better than tin cans and a piece of wire, but its reach is vastly more limited than other bands used by people who know exactly where to tune in an emergency.
At least as important as the radio is the need to have a good antenna(s).  Again, simply having an antenna isn’t enough.  You must know its strengths and its limitations and how to get the most out of it.  Many people think it’s silly, but those hams who take their wire antennas and throw them over a tree for Parks on the Air know exactly how to reach someone five hundred miles away with 10 watts of RF.
 
 

Transmit (encode) with the Travel Tone and set your receiver for CSQ, and operate simplex from your vehicle and save the portable radio batteries as long as you can.
Scrap the repeater idea. The repeater more than likely will require AC power which may not be available or if your repeater is DC operated than you will still need AC to charge the battery. Too much power consumption and battery up keep to worry about.
Of course this is in case if the fan can't operate due to the public power system being off-line for a long period of time.

I'm taking my HT down the driveway closing my gate. carrying all the other stuff sounds to heavy.
I would shelter in place where all my toys are...
WASQ406

In this case I’d leave the repeater in the truck   For these purposes it seams like a useless brick.  

I would not bother with the repeater. Anyone that can hit your repeater, even if there were no tones or they knew the tones, would also be able to hit your mobile radio. I would turn on the vehicle's AM/FM radio to hopefully get information and use the mobile or handheld to scan the frequencies it can receive.

As said forget the repeater. Just use simplex. IF you are going to use it when you get someplace else using the travel tone would be prudent. 

GMRS is primarily Wideband except for channels 8-14. 

Thank you so much for this information!

As far as I can remember, the Mocat designation for all the cb radios, antennas, and accessories except the in-dash stereo units. Motorola was still big into aftermarket AM/FM car stereos at that time. The 4009 model number was marked as Motorola and not Mocat. It was supposed to have a second receiver just for channel 9 monitoring. I think it had a button to activate the receiver, and did have a second squelch control. I don't know this to be true, but I think they was marketed thru the Motorola LMR shops in order to bid on contracts for state and local police radio sales. The 2000 series were 23 channel radios, and the 4000 series were 40 channels. I've never seen any documentation on decoding the serial number for the manufacture date. I think I saw somewhere on the net years ago that they actually manufactured by a third party. They were pretty good radios, but were expensive, and not as easily peaked and tuned, or adding power mics and such. I did have a 4009 that I got off of ebay, but it was pretty well beat up and did not receive.

All it does is temporarily (while pressing the button usually) disable squelch for receiving. It does nothing to remove the tones for transmitting . 

The Monitor button is just a shortcut to zero squelch. It's easier than adjusting the squelch to off then having to turn it back up. It's just for a momentary check if there is any traffic on a channel no mater how weak it is.

Well is it 3.5dBi vs 5dBi or 3.5dBi vs 5Dbd or something else?
The dBi gain number is based off an isotropic radiator.  Which is an antenna that only exists in theory.  It's a 'paper antenna' based on a radiation pattern that is a sphere.  Equal signal radiation in all directions.  Even a standard dipole will have gain over an isotropic radiator which is the dBd gain number. 
So in short they could be the same, or the 5dB antenna could actually be worse depending on what the gain number is based on. 
Now with that being said, Larsen typically has reasonable numbers attached to their products.  And they are based on actual testing in a RF free chamber so the numbers are reasonably accurate.  Some of the other 'no name' brands could be basing their gain on anything including a dummy load to pump up their gain numbers. 
One thing to understand here is what GAIN actually is.  And what it's not.  Amplifiers have active gain.  You put 1 watt in and get 10 watts out.  That's a 10dB gain number.  See that there was no i, d or anything else after the dB.  And dB is a measurement of CHANGE or difference between two things.  In this case signal.  Now power can be measured in watts, which is what everyone typically see's. But it can also be measured in dBm which is based on a 0dBm or 1milliwatt.  So 30dBm is 1 watt, and 40dBm is 10 watts,  which is a 10dB increase in signal. 

And LMR400 has 1dB of loss for the same length.

RG-213 on the charts I have seen shows 5.2 dB loss per 100 feet. at 45 feet it should be a bit less than half that. https://www.w4rp.com/ref/coax.html
Additional connectors do have issues with the potential for water intrusion and corrosion. For a temporary installation it is not much of an issue, but for permanent installations the better practice is to have a single run.

Each connector adds approximately 0.1db of loss. Other than the fact that at 50' you already have 4.4db of loss (64%) in power and sensitivity, the connector not a concern.

Depends on what the measurement is for. If you are modeling the RF horizon, you go from the bottom of the antenna. If you are dealing with zoning, then top of the antenna.

Ignoring the fact that Motorola once again tries to claim trademark rights in the term "Talkabout" for its line of FRS HTs:
There are two separate generally accepted concepts of functions that are useful when your radio is on a "repeater" channel; that is, set to transmit on a different frequency than the one that it receives on:
Talkaround and Reverse
Talkaround, which is primarily found on GMRS radios, allows the operator to be on a Repeater Channel, but by the push of a button, immediately convert it to the Simplex Channel on the same frequency.
Reverse, which is primarily found on HAM Radios, allows the operator to be on a Repeater Channel, but by the push of a button, listen to the Repeater Input frequency and transmit on the Repeater Output frequency
So using @WRWK524's example:
Operator 1 has his radio set to Repeater Channel 23 and transmits on 467.550 through a local repeater and listens to replies on the repeater output of 462.550.
Operator 2 has his radio set to Repeater Channel 23 and using Talkaround, he transmits on 462.550 and listens on 462.550 as well.
Now going to the OP's original question:
Yes, Operator 2 can communicate with Operator 1 because when Operator 1 transmits, Operator 2 will hear him on the output of the Repeater; while when Operator 2 transmits, Operator 1 will hear him Simplex because they are in close proximity.
This will cause some confusion by third parties listening to this conversation who are not in close proximity, because they will only hear Operator 1 and silence when Operator 2 transmits.
I often use this mode of communications when I discover a new repeater for which I do not know the access tone and I want to ask the Operator in close proximity to me for permission to use the Repeater and have him tell me the access tone.

Exactly!
No debate needed there!

If one is TX & RX on a Repeater using the same frequency as another who's only on Talkabout (Direct) on that same frequency, can either person TX or RX respectfully with one another if in close proximity? 
Clarification:  Thanks for your responses... part of this question should have been using the word respectively and not respectfully... sorry for the confustion!

Transmitting on the 467 MHz main channels is only allowed by the regulations to communicate through a repeater or for testing (or between two Fixed Stations), so if you mean for one person to be transmitting on a 467 main channel directly to another person who is then responding on the matching 462 main channel, it would technically only be allowed while testing, not as a full time communications mode.
Or did I miss your point?

That statement is a truism for all GMRS communications; not just the one posited by the OP.

Yes, but how respectful they are is up the operators.