I learned on an acoustic. Bought a $150 Washburn off musiciansfriend.com and was pleasantly surprised -- I just wanted something to beat to hell, but the tone was very clean.
I'm more of a rhythm guitarist than a soloist anyway, so acoustic works for me. I just taught myself basic chords and hacked my way through my favorite songs (which, lucky for me, are simple progressions like G - C - D). Not exactly the most difficult stuff in the world, but it kept me playing. Trust me, the novelty of "Hey, I can play a song!" doesn't wear off.
Do whatever you need to do to keep practicing, everyday.
Theory? Yeah, I guess I should work on that. I can pick up notes and keys by ear now, so I'm trying to train myself to pay more attention. Maybe I'll go browse amazon...