Ok heres what i'm thinking about getting for my 1990 honda crx

2 Alpine type X Subs 12' (SWX-1242D)
http://www.alpine-usa.com/en/product...odel=SWX-1242D
2 Alpine type x Speakers (SPX-137R)
http://www.alpine-usa.com/en/product...model=SPX-137R
Alpine Head Unit (CDA-9857) http://www.alpine-usa.com/en/products/product.php?model=CDA-9857〈=en&tab=D

I have a few Qustions though...
1: Do i need that much sub? or will i be good with 1? I want Lots of Bass but i don't want to go def.
2: What Amp do i get?
3. Will i need a extra battery for the sub?
4: WIll i need to amp the speakers?

This is my First System i have ever gotten so i'm not sure what is needed. (i know i have to get new wires too)

Thanks
Dan