As the legally required small print in the offering of financial products reads: "Past performance is no guarantee of future performance".

Since you will be guaranteeing the loans, make sure that line item is funded appropriately. 

It's time, money and stress for everyone involved.Can you visit the jobsite one time and have a face-to-face meeting where you pay him $1000 and sign a note that guarantees he will recieve the final $1000 after completion?

Personally, Id hire someone who will either straight up guarantee or all but guarantee you'll pass if they do the work.

My question is what guarantees should I expect before paying? 

@Jonathan Greene and @Mike Grudzien I agree but I was hoping to hear from some certified appraisers and if they would comp leased land versus owned land in an appraisal.Jonathan, you are guaranteed the land through the current lease period, but not guaranteed of a renewal.  

There is a tiny little link under "Account Details" that links to a more informative web page.

I couldn’t figure out who had to even sign the loan docs let alone the personal guarantees. 

One buyer could take up a lot of your time and energy and there is no guarantee they'll stick with the deal.

That's a good idea too, or a personal guarantee potentially if they signing as an LLC.