2) Bikes no longer have to be UCI compliant at Masters Nationals. Of course, this may change.
4) 24" wheels will also usually have better aerodynamics because of lower rotational drag. However this is probably offset by the higher rolling resistance of smaller wheels. Rotational drag is hard to test, and I can't think of anyone who has current rolling resistance data of 24" tires.
Another issue is that it's really challenging to find good fast tires at 24" since it's such a rare rim size.