We even had home depot call us each time our contractors were purchasing items, but do you really want to hear about all the nails and screws they are buying?

It sounds like your friend has 2 of your "essential elements" and you only have 1.But most importantly, having a clear written understanding of who does what BEFORE you start is key if you don't want to screw up your friendship.Good luck on what ever you decide to do,Arlen

I would like to learn as much as possible so I won't screw up to badly my first time out. 

Parents are usually much more forgiving if you screw something up.

A lot of people want to screw around toiling into doing everything themselves.

@Johnny George while Andrew is correct about how the due on sale clause works I personally don't recommend it unless you know your bank is not going to screw you over.  

The contractor really screwed up the floors, but kept telling me that's just the way they were supposed to look.  

If you get estimates wrong, and when you pull permits with the city and city says tear walls and change insulation to abate smoke smell, and you didn't include it on your repair cost, you're screwed.

Then determine how many buckets of compound, rolls of tape, screws, corner beads (inside and out), sanding screens/sandpaper, etc...You will need to do the same thing with each scope item to get an idea of what the material costs might be.

Also you better be involved with everything until its finished otherwise there is a good chance you will get screwed.