Agree on the price per scope of work, and allow for extra pay when extra work is performed. 

"Why does it seem like a scam, have you had others fail to perform in the past?

Lastly, I am in the process of getting my brokers license so I can perform property management services for my clients in addition to my own portfolio.

Please note that you are obligated to pay back their 401k (regardless of the performance of your real estate investment).As an alternative to taking the loan, you could even purchase the investment property directly using funds in your Solo 401k (assuming you select a Solo 401k plan provider which allows you to invest in real estate).

The Purchaser will be entitled to a refund of earnest money only if the Purchaser obtains an independent lead-based paint inspection or risk assessment performed by a Certified Lead-Based Paint Inspector or Risk Assessor, and the Purchaser provides HUD with a copy of the inspection report.This seems to me like if we got this LBP inspection done and there is LBP in the home, we can at least walk and get our $1k earnest money deposit back.  

Such cooperation shall include the performance in a timely manner of all of Seller’s pre-closing obligations under this Contract.

If you are daring, perform a group interview.

We did supplement investors rents or other costs where we feel we could have performed better as a company or even where we felt they had taken extraordinary steps of faith with our company (such as purchasing 5 or more properties) and we felt we could and needed to assist. 

Renters in place in October 1, property is performing as expected.

Offer them a fixed interest rate plus a performance bonus that is based on the profit (i.e. 25% of the net profit).One of the nice things about dealing with private individuals and not HML's is that you can get creative.