You’ll want to give them a chance to respond and consider the offer; if they seem amiable to carry back financing then you can proceed with more specifics.

However, the payout stubs only include a "Payout to Homeowner" figure less any expenses directly related to me, such as my extra cleaning request or items specifically purchased for the property.

The key items to understand are:- zoning and lot requirements, to determine how many lots you can develop at required lot size. 

The only repairs you'll really see on these is wearing items like couplings and such.

He's open to financing and we agreed he would carry 30% and I'd finance the other 70% through a bank or other lender.I'm starting to get advice from lenders now though, that I'll still need to come up with my 20%. 

Do not question an item. 

It is necessary to first time each year to establish base numbers for $ft of each item and labor costs.

The process is the same but you do not to take note of 1 item.

You also save on carrying costs by selling all at once.

One wrong item comes up, wether it's a structural or foundational issue and your deal could be shot.