Help me build my first system!

[Aleks976]

Hello all!

*Disclaimer, I am a total noob*

I have a 2002 Alero Coupe with the monsoon amp and have blown out half my speakers (one 4x6 and both 6x9s, car was used when I bought it). I want to put a nice sound system in it without getting premium products. My questions are this:

4x6s or 6.5" in the doors? (won't the window get in the way?)

Should I buy a cheap $80 Kenwood headunit and is it good enough or do I need to spend more?

If I put a 12" sub in the trunk, would I still need to get new 6x9s?
If I get a 12" sub, please recommend an amp.

Thanks!