I don't know for sure, but I doubt the basic pay can be altered under the union contract
I dont know either, but if the company cant pay you the (lesser) salary scale for the type you downtrained to then whats the point? 747 pilots being paid 747 money to fly 767s or A320s? Cant see the company doing that.
Lots of retraining/sim time and musical seats to save a few allowances? Allowances arent type specific anyway are they? I would have thought they are trip or duty specific, regardless of the type that flew it.