It sounds to me like you need to take a trip to your local guitar-tech.
Lowering the bridge probably caused the rattling(fret-buzz), plus, you truss rod might need some adjustment. The intonation can go bad at any moment since wood never stops moving, and especially if you change string gauges or play around with the bridge. The strings might be "pinched" either at the bridge or nut, which can cause your strings to break prematurely. Conclusion? There are plenty of thing that can be wrong with your guitar, which none of us here can diagnose over the internet. Your best bet is to have it looked at by a professional.

Going from a fixed bridge to a floyd style bridge will cost a lot of money. Your guitar will need routing to make the bridge fit, and the bridge itself will cost nearly $200, plus a nice work fee for whoever does the job. All in all not really worth it, you're better of buying a guitar that already has a floyd rose bridge installed.