Drive train questions

[Bjenks548]

I'm running over some possible drive train ideas, with physics not starting till next year i have a few questions.

1) What (if any) advantages is there to having 2 gear boxes with 2 cims in each as appose to 4 gear boxes with a cim in each?

2) Just wondering if this would work. A drive train with 2 mecanum wheels in the center and an omni wheel in each corner. Only the mecanum wheels are powered. If I'm thinking of this correctly you always are crabing with no way to turn your robot. Is this correct? I'm not looking for people telling me how stupid it would be to have a robot that can't turn, i know this, just would this happen?

3) In the two years I've been on the team we have not used pneumatics. Just making sure, the cylinders can be fully extended, fully compacted, but can they be put somewhere in between? Like half extended.

I'm sure I'll come up with more questions to ask about drive trains, that's all i can think of right now.