I like the design!
Same question, why 5 shafts? If you lose chain you could be unable to drive any of the wheels, whereas if you direct drive a wheel you are guaranteed at least one wheel under power.
Second, Are you using the w pattern traction wheels?
http://www.wcproducts.net/versawheel/
Third, Why go with exactly 112" perimeter? This may sound dumb, but why go as close as you can, because a tape measure may be short or you could bend your frame making it bigger... (my team usually goes at 111" to be on the safe side)
Fourth, I have not worked with sheet metal before, but is it strong enough to support the wheel bearings without versa blocks or something to that extent? i have seen it done with thicker metal, but not sheet metal.