Thanks for reading and any advice you can extend ! 

Thanks for reading and any advice you can extend ! 

We got it under contract, but the inspection determined we would have to replace a garage/basement wall and we had to extend the deadline to commit until this Friday to get some bids for repairs.We have reached the seller's bottom dollar of $280k ($15k below listing).

I would recommend keeping your older ones open to extend the average of the age of your credit and increase your available credit but keep the amount owed to a very low percentage of your credit limits such as less than 15%.

If a purchase contract is not possible at this moment, are there other ways to at least have some sort of an agreement in the event he decides to sell in the future, some sort of a "Buyer's right of first refusal to purchase" for a set price and duration that may work to my advantage and still give the seller the freedom to not sell?

A month-to-month lease automatically extends.

To do this I make agreements with tenants to extend their lease a couple of months as is and they allow me to do some prep/turnover work and find a replacement tenant before they vacate. 

Every landlord should have a method, that can pass legal scrutiny, to get rid of undesired tenants .Just do not do something stupid like indicate that you are not extending their lease because they have an emotional support animal.BTW we have a unit with a legit support animal. 

Does she/he have to be added to the mortgage in all circumstances, regardless of expected duration of stay?

Tenants should be held responsible for duration of lease until you find new tenant.