Amps = power. Quality = source. Wiring?...go find some lamp cord. It's good copper and probably free at the land fill. Wrap it up to make it look as pretty as needed so you feel better about it and you're done.
Get some Sony Xplod amps or something rather...matched with a nice deck and you'll be fine. Typical output from "cranked" systems relates to about 16w per speaker and ~100db.
Audiophile systems are only as expensive as the person wishes them to be.
Sound deadening? That involves MLV and foam. Mass loaded vinyl will add weight to resonating panels which will then transfer their resonation to lower frequencies. MLV only needs to cover 25% of the center of said vibrating surfaces to remove 95% of the problem.
You match the MLV with closed cell foam to dampen the noise. Majority of the noise is transferred from the road to tires, through wheel wells, and eventually to the cabin. Fight the source.
You can have an amazing system for ~$500 if you're a good shopper
The real research begins when matching speakers with installation goals. Don't skimp on good installation practices and ask people like matt to figure out how to match speakers for said purpose; i.e. music, burps, SPL stuff...etc.
