After working on my first project for about eight months, I believe I'm still a newbie myself, but let me see if I can answer some of those questions for you.
1. I'll let someone with more experience tackle this one.
2. Yes. I've done it. Be aware though that you'll have to get to a really high grit before it will look right. At that point, you're more or less polishing.
3. I say no, but as noted, you can use wood too. However, plastic is much easier, imho.
4. Yes, the trussrod is contained entirely within the neck. Are you sure that's an Epi LP Standard? It looks like the LP Studio. The main reason I ask is that the Studio should have a bolt-on neck (bolted in) vs. a set neck (glued in). If it's a bolt-on, take it right off. Be careful with it, but there are no unusual precautions you need to take. In fact, if you want to get into guitar building, I say take the whole thing apart and put it back together again. You'll understand the guitar better afterward.
5. There are a number of ways to go about that one. If you can't find one, you may be able to make your own. Go to the main page (projectguitar.com) and check the tutorials. There's one in there somewhere.
As a final note, I think almost everyone here will agree that building slow is a good thing when you're learning.
Good luck!
-Dave