A few questions about my car stereo?

I have a 2000 celica gt with a jensen flip out headunit. 2 12" alpine type r's with an infinity 1300 watt amp. I also have 4 Jl audio 6.5's, and 2 stock tweeters all hooked up to an alpine mrp 160 watt amp. First off I would like to know why my speakers (not subs) start to crackle and sound like static whenever I play my system for more than 15 minutes fairly loud. I believe this is distortion but I'm not exactly sure. My car rattles like a ***** from the inside out, but the most prominent rattling comes from the rear view mirror, which I can't figure out how to get off. I would like a solution to stop the rattling of the mirror and also an explanation why my speakers begin to crackle even though they are top of the line speakers hooked up to a real nice amp. i just don't understand. thanks.