1 – I am not sure. The thing is with short sales, and even REO sales, the lender can set the commissions regardless of what is advertised on the MLS. So I do not know if a lender on a short sale will knock down the commission if they see the listing agent is doing both sides.
2 – No you are not obligated at all. Fire off as many offers as you like. You don’t even give a deposit check, just a copy of one.
