Rus and deal hunter spelled it out very well and I agree with them. I will say that you can do pretty good on a short sale but you need patience patience patience. Any buyers that I work with that like short sales get the same advice… make your offer, then forget you ever made the offer…go look at other homes.
Your realtor should have already answered all the questions you posted here. Make sure they are experienced with short sales. If they have short sale listings that they are trying to sell that is the best way for them to get acquainted with the short sale process.
You also should consider that you may get a good deal now, you may get a great deal if you wait another few years.