It forced me to reach out to developers, to engineers dozens of local builders and most important like minded individuals.

He had done this to force out his old cell mate who was staying there 'working', I guess the dynamic between them had begun to break down.

A PMC can get a bad reputation really fast and be forced to use only the WORST contractors that are unreliable hacks. 

Since the price of a multi unit is double or sometimes 3x the price of a single family home, would it be smart to start off with a SFH and scale up from there or just make the leap into a duplex that I can force some appreciation with minor repairs.

Most sellers only care if you close so you can usually use another form of capital stack other than what is on the agreement, however, the seller can force you to use the originally agreed-upon payment method. 

Our contract is enforceable, and I can sue Don to force him make the payments that he agreed to make. 

I'd likely just agree to break the lease with a couple months of rent as a penalty rather than force these people to continue being tenants in my property....you never know what will happen to the condition of the property.

Do you think that is fair - to be forced to pay for your manager's mistake?

This could also force your current tenants to lose their jobs and need to move out and then you’d be in a real bind.

I was suggesting that if you wanted to do a 1031 of a property held in a LLC, they would be forced to also do the 1031 exchange.