1) None (since I learned how to ride rollers)
2) None
3) Yes
4) 50 - 75 over the price of the rollers

Hard to say, imobilize the top of the bike and the wheels slide out
from under you. However Tacx markets a stabilzing device that clamps
to the handle bars. so maybe my thinking is off?

As an avid roller rider this is interesting, I'd be interested to see what
you come up with.

Marty