Those types of details are worked out in the writing of the contract. You need to work closely with your realtor to negotiate what you want from the seller as well as what the seller is willing to do to complete the sale. Of course this largely depends on the price, short sale?, bank owned?- so many variables. This process is a balancing act - be sure you are working a realtor you are comfortable talking to and gives you the time to discuss your concerns. Of course your realtor works for you- you can ask for anything during this process. It doesn't mean it will happen or that the transaction will go through but, yes you most certainly can ask.
'Results through Performance"
Russ Lyon Sotheby's International