My stereo plan, need suggestion & help

Right now my stereo is just stock, and I have a Sony Xplode 500W amp sitting around that I bought from a member, the LOC that came with it was broken. Anyways, here is my plan:

1) Either keep the stock HU or get the OEM 2-Din touch screen DVD so that I can keep the steering wheel control. The only thing that's holding me back is that I don't want to wake up one morning to see my window smashed and dvd stolen.

2) Since the LOC is broken, I wonder if I can just use the high level input on the amp instead. Can anyone confirm this please?

3) I know 4-way speakers don't mean they are better than 2-way or 3-way but I like the idea of having tweeters / super tweeters since I don't listen to songs with heavy bass. I saw some Pioneer 4-way speakers on eBay for $80 shipped, seems like a good deal. I don't know if I should use the same 4-way speakers for front & rear. Any suggestion please?

I don't know too much about stereos but this is my guess, please correct me if I'm wrong.

1) Put the amp in the trunk and run a long power source from the battery and fuse it.
2) Run wire from the output of the HU all the way back to the amp.
3) Then run the speaker wires all the way to the front door & rear door speakers.
4) It seems like I won't need any RCA wires because there is nothing to plug them into, do I just use any kind of wire?
5) Where should I hide all these wires? Should I try to avoid power source along the way?

Thanks and hopefully I can get this done by myself, I'd like to learn and try this myself. Most importantly, I don't want to pay hundreds of dollars for some shop to install them.