Can he end the lease early if he gives 60 days notice, or is the landlord able to make him pay through all 12 months?

If he can he just earned your business.

How can he cloud your title and threaten to sue if his contract has expired?

@David Fernandez,  if Neil wants to move out after 1-2 years of living in this newly converted ADU, can he still rent it out? 

A few went through the drywall, but they left.I'll never forget when i bought a property and a non paying tenant said to the seller "Can he do this?"

If you fixed it up, is your father going to feel the same way about the house, and for how long can he live there unassisted?  

But if I want an inspection period, and I write it in the special provisions, AND the other party agrees and signs, then can he or the state later say that since there was no payment made, the contract could not have allowed for an inspection period, OR say that inspection periods are not allowed even if added to the contract?

Can he sue me for the money?

How can he not know for sure?

In order to benefit from the 10% down payment option for owner occupied buildings, is there a minimum amount of time that he must live in the apartment or can he move at any time?