Happydude

Hello everyone,
i'm pretty new with the whole car owning scene, just got an '07 civic and i would like to put a sub and perhaps replace the standard speakers just for kicks.

I have a few questions:

1. Is it easy to install the sub and/or replace the speakers in a 2007 civic sedan?
2. What's a good speaker and sub brand for quality as well as power?
3. Is an amp required and what is it's purpose? and what's a good brand for an amp?
4. If i didn't want to do it myself, where would be a good place to go get them installed in the GTA?
5. where is a good place to go buy the parts in the GTA?


Thanks in advance guys.