Time is a factor as I need to decide weather to purchase or terminate the contract by this Friday.

Make sure it explicitly explains the process for termination if you are unhappy with their services, but especially if they violate the terms of your agreement.3.

The buyer can elect to terminate the contract before short sale acceptance.Short Sales are very rare in this market right now.

We mutually agreed to terminate the lease early and we were glad to get rid of them.  

Many businesses would not survive if they kept threatening to terminate relationships with late (even habitually late) paying clients. 

The lease has a statement that says "If this property changes Ownership due to sale, foreclosure or deed back to the lender then this lease may be terminated with a 30 day notice unless the new Owner agrees to continue the lease and both parties wish to do so".

How acceptable is it to add an addendum to the renters contract that if the property is to be sold an x months notice will be given and the lease will terminated?

You don't have to say you want to come over and check the air filter or the smoke detector batteries or whatever to keep an eye on the place.

A lot of people who rent short term in the high end condos rent every year, and typically have right of first refusal to book their time for the next year. 

Been in the solar industry for 4 years.Typically the sellers options with the lease are:1) Transfer it with the sale of the property (which assumes the buyer is qualified and willing to accept the lease - qualification usually based solely on FICO score).2) Pay off the lease (usually according to a payment schedule, which may include early termination fees).Option #2 can be really expensive.How old is the lease?