Adding 4 channel amp, which one to get???

[boomin]

I'm looking to get a 4 channel amp as a little project to do since i finally have the week off (spring break). Can someone help me out here i really want to get this done. My budget is preferably <$150, but im willing to buy used.

I just have some questions, if you all could help that'd be great:

1) Which one should i buy? My front speakers handle 65 watts RMS and the rear ones 30 RMS. I'm guessing i could just get a 50x4 RMS amp and turn the gain up the gain for the front and turn down the gain for the rear?

2) my front speakers are for 3 Ohms, my rear for 4 Ohms.....how would i wire them properly? (if possible??)

3) Do I need a new power wire, or could I just run it off my current one on top of my sub box (buy like 2 ft of wire and have both hooked up to the sub amp one end going to 4 chnl, the other going to batt)

4) What's the install like? can I just ditch the current stock wiring (just un plug it), and use RCA's to get input signal to 4 channel amp, and from there just get fresh wire all around for output?

5) I have 1 RCA running to back of HU....since it has both red and white on it, and only one is in use (white) could I just use that other single RCA (red) for the new amp?

Thanks for reading, and if anyone could help out i would really appreciate it...right now i was thinking about going with a kicker 4 channel for $150, any thoughts?

My car is a 2007 Honda Civic EX Sedan. Currently has a Kenwood KVT512 headunit, and a alpine sub with MRP500 amp. also has components (3 ohm, 65 watts RMS) and coaxial's (4 ohm, 30 watts RMS)