You might want to check out the Drive Train references in the middle of this page.
http://cheer4ftc.blogspot.com/p/drive-trains.html
Particularly this one.
https://docs.google.com/file/d/0B0zY...XpyN1U/preview
They're written for FRC but are very applicable for FTC too, particularly the advice about going for a simple design when you're rookies. It's very easy for rookies to underestimate how hard it is to build and program a complicated FTC robot and end up with a half finished robot that's never been tested or driven in practice before a tournament.
Good luck!