Car System

1. Should you over power your speakers?
if your amp puts out 200 watts per channel, should the speakers be 175 or 150 watt rms?

2. I see most speakers are 92db.
so the only way to get it louder is to add more speakers?
or does more watts equal louder?

3. Does the size of the speaker really matter?
Ive seen computer speakers that are really loud and sound good and like 2 in and like 15 watts.


thanks in advance