Now, the time is coming close for us to make arrangements for the home, and we are torn between selling to use the extra money to pay off a few bills/loans or sticking with the original plan of renting it out as an investment property.

I think you have to give them a little time to make arrangements.

Are there any verbal agreements or arrangements between the current Landlord and Tenant?

He's asking too much for me to wholesale it, but he said he's open to an arrangement where he allows us to build a SFH home on the land if he gets a percentage of the profit once the land/home sell.What is that kind of deal called?

Were the tenants previously on leases that went month to month or is it all a verbal arrangement?

The best part of this sale was the seller being very easy to work with, since he was happy with our price and our customer service helping him understand the contracts, make moving arrangements, etc.

The best part of this sale was the seller being very easy to work with, since he was happy with our price and our customer service helping him understand the contracts, make moving arrangements, etc.

Would this arrangement cause any issues?

I will tell him they will sell the apartment to him a market price (which I will explain will be in his best interest), or it will be sold to an investor as-is and he make his future arrangements with them. 

They arranged it.