What type of Strat and what year is it? The newer Strats do not have to be screwed in, you can just pop them in and pop them out (the best way to tell is look at the end of the bar. If it's pointed with a notch above it, you can just pop it in). As far as putting a new tremolo in, that's a pro's job at the shop. You run into all kinds of problems. Normally (and I may be wrong on this, so anyone correct me if I am), the Floyd Rose is a bit deeper than the normal Strat tremolo, so they may not be able to put one in without have to physically alter the body. They do make Strats with a Floyd Rose installed already (the Richie Sambora sig series, and I think there's one more. If you don't want to fork out the cash for a Fender, Jackson makes very good Strat style bodies all with Floyd Rose licensed tremolo's.