To answer your first question....Step 1 is to simply ask the agent how long he/she has been in the business and how many short sales he/she have done. This is not the first market we have had where short sales have occured. I personally did several almost 20 years ago when we had a severe downturn in the market. As far as an agent representing both the buyer and seller, it can be done with full disclosure to both parties, but if you prefer that not be the case, you can request that in your listng contract. However, in today's market, I do not think it is in the best interest of the seller to exclude a buyer your listing agent might have.
To answer your second question...It is difficult to predict what a bank's response will be to a short sale. They are handling an inventory of homes and it may depend on factors quite outside those associated with one particular property. The best way to deal with it, though, is to have a market analysis using very recent sales of homes very similar to the subject property to present to the bank with your offer. The bank will then hire either an appraiser or a real estate broker to do their own comps. It can take several months before a bank decides to approve a short sale and often times a buyer may not have the ability to wait that long. If the property is in reasonably good shape and in a desireable area, the banks are not giving them away. They bank will also need to see from the seller that they cannot afford to pay the difference between the offer and the amount owed. They will review the assets and income of the sellers and that will also play a part in determining if they will accept the short sale. As youc an see, there are a lot of variable at work here, but patience is key in getting through it.