Unfortunately, you may have a hard time enforcing anything about "guests" unless policy/procedures are outlined in your lease.  

You’re acting as the assignor, so once the assignment agreement is signed, the buyer takes on the financial responsibilities outlined in the PSA, including the EMD submission.

Do I draft the contract price for higher than the actual build price that would include our estimated profit (sell price) or would a separate agreement between the lot owner be sufficient enough that outlines the deal since we don't know the actual sell price until it goes to market?

Or, do he need to send some type of escrow instructions that outline 1st position, will fund after all docs signed, etc?

In fact, a common colleague of Chris and mine worked with them for a few years but departed once he learned of the issues outlined above.   

Are there any good outlines or templates for an introduction letter to the tenants, or any major points I should make sure I put in my letter?

Hopping on call with our realtor tonight to outline our next offer!

The contract should have outlined the amount of earnest money you deliver.

i didn't even know auctions gave opportunities to actually have access to properties beforehand.Given your line of work, i would say that you are uniquely positioned to work well in the outlined situation.

Great outline.