Something this complex is difficult if not impossible to explain in a forum. The task is difficult and requires experience, the correct tools, and knowledge gained by previous installations. I can make a turd shine but I can't do squat with tunes/electronics and I know it.
If you share the same misfortune then shop around for a good shop to do the installation that will back it up. Prior to that shop for good components (google is WONDERFUL). Buy what you can afford. From what I understand Sony components and speakers are not at the top of the heap but if they sound good to you and they are affordable then buy them.
If you asked 50 people here what brand to buy you would likely get 50 different opinions. Do what is right for you but consider professional installation from a highly reputable shop. I am so very glad I did.
