Dude, you have taken the first step, and come to the right place to get all the info.
I hate to do this, but, you gotta learn. You gotta learn the

, live the

, be the

.
If you search on these forums you will find everything you will need to know about the list you have been given. The posts will often times have reviews, pros and cons, and places to buy these things.
Buying from MP3Car is always a good option. The service is great, and it helps support this site. But certainly, if you can save money, no one will fault you for buying elsewhere. You will quickly learn that most people here are, shall we say Frugal.
In the least, once you have the name of the product, you can search the web using

to find places that sell the items. You can also use googles search called frugal (It is right above the google search box) to find prices and places to buy.
While I am no expert at the computer thing, I am pretty good with wiring a car up. Been doin it for years. If and when we have your install day, I will do my best to attend, and help out.
Goodluck. And, if after searching, you still have questions, we will all be happy to help.
Also, you might want to take a look in the Newb section of the forums. It is a great way to start.