To be honest, if you want to enjoy playing you should play stuff that you like. I taught myself to play starting with a copy of the sheet music to Phantom of the Opera that my dad had bought – not the “easy piano” version, but the real one. Started with picking out the melodies, added simple left hands, went from there. From what I’ve seen, a lot of people get turned off of whatever instrument they’re learning because what they’re playing doesn’t sound terribly much like real music.
If you’re looking for free sheet music on the 'net, then yeah, it’s likely to be limited to classical due to copyright thingamajigs. Another possibility, though, is to get a program that can change MIDI files to sheet music. I use Noteworthy Composer, but that’s because it’s what I use to print all of my sheet music. I’m sure there’s programs out there that specialize in MIDI to sheet music conversion.
In terms of breaking your hands apart and such, all I can say is practice each of the hands’ parts separately a lot before putting them together. Memorizing helps. Also, try stuff with really simple left-hand parts, or simplify what’s there.
If you have the cash to buy a book, I recommend one called Easy Classics to Moderns or something like that. I think it’s relatively inexpensive, but then my copy’s about twice as old as I am, so I’m not sure what it’s going for these days. Also, find out if any libraries in your area have sheet music, and make some photocopies.