While Limited Lodging is a permissible accessory use to Household Living, it is not permissible unless (i) the unit is the primary tenant's principal residence and (ii) the tenant lives in the unit for more than 6 months.

The next question is permissible and non permissible closing expenses. 

My son’s friend lives in Palenville and his parents were telling me how difficult it was for a dollar store to get permission to build there.

You can't legally do anything until the sale closes, but you may get permission from the Seller to introduce yourself to the property manager and tenants.

So there you go, that should make $1300 permissible if the fair market rent is $1600. 

You'd want to have a notarized document giving you permission to make any inquiries on the mortgage.

If you feel like you need permission to enforce your lease, then consider it granted.

It is also permissible by regulation to 1099 the GROSS rental amount to the owners and have them deduct your commissions on their schedule E.

The city is giving permission for the people that can afford (with both land and $) to, an opportunity to house homeless people in their back yard.

But unless this is a commercial loan (e.g. 5 units or more), anything requiring permission to obtain a second is unenforceable.