first off, welcome!
use the search function in the upper right part of the page, enter in your car and search. Do this for all of your questions, it will save you a lot of hastle from people like myself...lol
there is a LOT of information avaliable on this forum, use that to your advantage. You will learn a LOT more from researching than you will from just asking questions.
Now onto your specific questions!
1. We need to know the exact modoel number of your amplifier. That will tell us if it's a 5 channel amplifier, if it's not chances are you are asking for gold from wheat in trying to get it to powe all 5 channels.
2. Search, both here on the MP3car.com site and on the web, there are plenty of sites out there that will hold your hand through the install
3. Search, both here on the MP3car.com site and on the web, there are plenty of sites out there that have good deals on parts, just take a little time and look around!
Again, welcome! and be sure to post pictures of your install and final product!