Yes, if it has a decimal it is always CTCSS.
For the other questions, keep this page handy. If you are like me, you will forget and have to refer back to it from time to time.
Don't know if it is small enough but this is what I use.
I've seen some people on this site complain about this antenna but it has been working great for me.
@Billz Welcome to myGMRS.com. Lots of good people here who are knowledgeable and helpful. As @SteveShannon said @marcspaz video is a good one to start with.
If you prefer the info in written form you might give this page a shot.
I will also second @WRUU653 on HamStudy.org. That is what I used for my tech and general and I'm using it to study for the extra.
P.S. I've been kicking around the idea of writing a PDF of GMRS basics and FAQ. Maybe I'll go ahead and dive into that. It would be something good to have.
This is starting to make sense to me. I don't think I've ever seen a serial cable that delivered data and also power. There are however USB cables that deliver data and power.
That being said, I think you are right that you will have to get the other cable so that you can deliver the power and data. Or just connect power and data separately.