Man, honestly, if your not real knowledgeable, I'd take it to a shop and give em thirty bucks to hook it up.
If your power LED on your amp isn't powering up, then either your power, remote, or ground wire is not connected somewhere. More than likely it's your remote wire.
As for your rears, does the whizzing sound change pitch with the revs of the engine. If so it's either a ground issue with the speaker leads, or your amp is dying a slow death.
The reason I say take it to a shop, is because they already know all this, and can diagnose it quickly with the help of a multimeter and all the other fun toys we have on hand. I can walk you through it, but in the end it's probably worth a few bucks for peace of mind.