tx is the transmitter or remote, rx is the reciever. as far as good trex 450's, i would recommend either the 450 se v2 or the sport. really i would go with the sport. you can often find them for around 400 bux, comes with all three cyclic servos, tail servo and a gyro plus motor and esc. all it needs is the transmiter and reciever. i started with a dx6i that came with my blade 400, but i ran into issues with it as many folks do. i now use a dx7 and love it. has a 20 model memory so it will last for long time. plus it is a 7 channel incase you get into nitros down the road. its a very nice tx for the money. if you get it without any servos, it costs around 200. a spektrum 6100 rx i believe is around 60. its alot of initial cost, but its well worth it, and you it will pay in the end. plus, once you have a good tx, your set for the future.

also, if you havnt done it already, there are some very handy vids over on helifreak. here is a link to the heli skills and setup 101 vids. has a lot of good info for setting up ccpm helis and transmitters and other things. there are also many build videos in the finless bob heli tech room.

[link]http://helifreak.com/showthread.php?t=41692[/link]