for quality drivers liike dyn's get the very most power.
NOTHING SOUNDS BETTER THAN POWER!!
If your drivers have a an RMS limit of 100 watts, I'd say 500 watts should sound great
Headroom is key for musical dynamics.
Impedence is a tricky game you may not be ready to play. Impedence is very important when speaking in terms of power management but an 8 ohm driver with 96db of sensitivty is going be louder and cleaner than a 4 ohm driver at 88db. Not to get too tricky but don't think these are the final answers they're giving you, just good enough answers.
You're in Tacoma...just stay away from Car Toys and Foss and you'll be alright
Did you get Dyn's from around here?