That's a lot o questions, there is a pretty good post at the head of this beginners forum that list the trainers that are out there, but I try to answer you the best I can.

#1 If you go rtf, most of your other questions wont matter because they already have specific brand radios and engines tied to that manufacturer. That's not a bad thing and they are easier to assemble, just make sure you like what they come with.

#2 High wing with flat bottom, it creates more lift and thus, slower stall speeds. It also makes the plane very stable in flight.

#3 I prefer glow or gas to electric but its just that, a preference. If you by glow you will need a starter, fuel filler/pump, glow starter and a few other things. Electric will also require additional purchases like extra batteries a good quality charger, cell-balancer for li-po, stuff like that. I like to hear my planes fly, so I fly glow.

#4 If you can swing it the new spektrum DX7 will be the only radio you may ever have to buy. It's sythesized so you don't have to worry about messing with other peoples frequency on the flight line and It's also a 7 channel computer radio. But it's about $310. You can buy a JR or Futaba standard four channel radio/flight kit for around $110-120

#5 Buy the best you can afford so you wont have to spend it later, minimum is four channel

I will address your other questions shortly, I must go to work.[&o]