You had no contract/agreement with this cleaning company. 

The general contractor should provide this work agreement.

Your doctor friend could do a loan to the entity plus have a a JV agreement for the 50/50 profit split.

Rent adjustment may be a consideration compared to the last lease agreement, but that can be changed over time, a long term tenant is more important than that potential 50 dollar difference per month right now.

2 year lease agreement within a week of posting the property for rent despite the start of covid lockdown.

As a Buyer, you don't pay any commission unless you have a Realtor that forces you to sign a Buyer Broker Agreement.

Or maybe find a partner who would buy with you and then you can structure an agreement where you buy that partner out over a specified period of time, with periodic payments or something agreeable to both of you? 

I think it matters most in what entity signs the purchase agreements.

How do you set up an agreement for someone to respond to a rental for minor maintenance?

Unfortunately, we did not have a good feel for their processing & underwriting – their process takes a minimum of 4 weeks, the sales person told us 14 days; we had an agreement with the Seller to close quickly, so we made the purchase in cash.