So...on tones...ctcss is more common, and usually expressed in hz, almost always with a decimal. 141.3 hz is a common one. Dcs will be 3 digits, often with a letter N (normal) or I (inverted). Either will get saved on the channel you're using, and these are effectively the "key" into the repeater, working kind of like a filter....signals with the right tone get through, and others are ignored. (If your radio is set with a receive tone of 141.3 hz, you'll only hear signals from someone using 141.3 hz as a transmit tone, for example)
On programming (disc and cable), it isn't a necessity, but its useful, especially with one that lets you receive such a wide variety of bands, you may want to add things like local public safety, or pre agreed presets (channel/tone) to use with family. At least on the kg1000g, you can likely accomplish the same manually via the menus (not 100% on that, but others that own one may be able to confirm).
Hope this gives a little bit of clarity.