Sounds like you know what you're doing. If the guy is paying for materials and any specialist labour then seems like a decent offer, just be careful he doesn't expect you to work on it 24/7 for his free rent!
Your parents house sounds pretty sweet, get some pics up
Ha, someone is going to have a surprise when they open that back out. It was already screwed (You can tell that the fireplace had been removed totally at one point, then that crappy one you can see in the photos was put back in, then I came along and added another layer on top).
What red tape have you come across? Was it your house that had the crack in it?
Keeping motivated is probably the hardest thing, especially while working a full time job. I think I might have had about 6 weekends 'off' since I started, usually down to having to go to weddings or something. Not much advice you can give on staying motivated, it was a case of never stopping for me. If I stopped, I found it harder to start back up.
Those slabs look awesome, good luck cutting them! How about just laying them a bit like they are, but with gravel between them? Might save a bit of time and look pretty smart too.