I'm just as much a newbie as you, so take what I say with a grain of salt. I chose servos because there is less chance of an error ruining a long run. I also wanted something pretty powerful for not to much money and found a good deal on them (but they are large and heavy). I think it is a good idea to always buy servos with an encoder on them. I wouldn't bother with them otherwise.
I'm going to use Rutex controllers instead of Gecko's because they look like they have more bells and whisltes and less wiring. The Rutex controllers are made to use servo's.
I haven't seen too many kits that include the motors, controllers, etc...the few I have seen are really for smaller machines than I'm building so I never paid much attention.