I'd drag out the letter that outlined the work and remind him what he agreed to.

Were planning on setting up a separate LLC and outlining terms legalling for everything.

My first goal is to find an investment property that I can finance with OPM, I have confidence in my network that if I can find the right deal where the numbers make sense and have it outlined on a business plan that I can raise the down payment.

I suggest you give them a call and they can outline the costs in detail.

Who pays for the title insurance policy (a title check is normally not sufficient) and for other closing costs is specifically outlined in the contract.

He mentioned that this could be a negotiating tool to help outline your terms.

A lot of people have been successful with the Dave Ramsey baby steps plan outlined here: https://www.daveramsey.com/baby-steps.

I am guessing you have outlined to all electricians that you expect permits to be pulled and they are alright with that?

The owner finance addendum will outline those terms and whether or not the buyer can refinance on their own. 

I think this is the scenario you outlined below.The bank would no owe you anything you would simply have $90k in debt on an asset worth $150k or $60k in equity.