Mecanum Specifics- Layout, Ratios, etc

[craigboez]

As a second year team, we're getting prepared to start experimenting with our first Mecanum drivetrain. We have a set of the 6" wheels from AM en route, and while we wait we were doing some digital design. I have a few questions that I was unable to answer from previous threads:

1. Does the layout of the wheels have a big impact on the overall performance of the bot? We could either lay them out in a square or rectangle - does it make a big difference (especially from a programming standpoint)?
2. Is maximizing the footprint a big deal? Put another way, should the wheels be pushed as far toward the corners as possible?
3. What have you used as a successful final gear ratio, and what type of gearbox did you implement. A few earlier posts suggested direct drive off a Banebots transmission, either 12:1 or 9:1. We don't have any of those, and rather than dropping $400 on some trannies we'll probably try to adapt the Toughboxes we've got. There are some good ideas floating around, just wanted to get a feel for what others have tried.

Thanks for the support.