Can you include property management terms in purchase contract?

[Daniel Kong]

Hello! I'm in the middle of buying a rental out of state right now. The person negotiating the sale knows the seller and also is managing the property. He is guaranteeing me the first year of rent, if I purchase the house. He is also willing to lower the purchase price of the house, if he cannot find a renter at the price we are looking for. Is there some way to include this agreement in the contract to purchase the house? Has anyone heard of something like this before? There are a couple reasons why I'm a little hesitant to pull the trigger.

1. I haven't met the person negotiating the sale in person, and won't be able to. 

2. The promised rent is a little higher than the average in the area, and it would also be a Section 8 renter.

What do you guys think?