#1
Can you fit a fender lsr roller nut in a squier (affinity) strat?
#3
I think the roller nut's a little bit bigger than a regular nut, so you'd probably have to do some widening of the space where the nut goes in. That's just my guess, but Warmoth differentiates between a regular neck and a neck fit for a roller nut. (Which you can see here )
#4
The current LSR roller nut can retrofit a standard neck, or replace the old style roller nut.
Beware, though. The LSR nut is 1 11/16" wide, and CANNOT be made to replace a narrower nut. The string spacing is fixed.