[Tristan Lall]

With regard to driving them together, it's feasible, but be aware that you'll limit yourself a little bit in the area of complex motions (because you can't get all 4 wheels spinning at different speeds). This probably won't be too big a deal, though, because it's difficult to control that sort of motion by hand. In autonomous mode, it might limit your options a little, but you should be able to work around it.

Also, if you steer them together, you're limiting yourself (under most circumstances) to either a lot of sliding, or to translations only. As long as you're happy with a skid-steer component to some of your turns, this is quite possible. In fact, most robots forego the ability to steer modules independently, because they'd rather use the motors elsewhere, and don't really need fancy rotational moves (like orbiting an object while revolving around the robot's own axis).

I'm trying to remember if 47's 2002 robot had 4 independently-driven and independently-steered modules; I think that it did, and that would make it one of the very few with that capability.