Real Estate Short Sale

I have a real estate question about short sales. If you know anything about investing in real estate, please read this.

I found this really nice 3355 sf house in Arizona, 5 bed, 3 bath and it is listed for $299,000 as a short sale. A real estate person told my mom that short sales never go for the low price, and that they always sell for more.

So my question is, can you get a short sale house for the listed price?

What is in it for a bank to not allow a short sale?

I know several people whose banks will not allow them to do a short sale instead of being foreclosed upon. Is there something in it for the banks (tax write-offs?) that makes it more beneficial for them to deny short sales?
Some of the people have had a buyer ready to buy if they were allowed a short sale too.

I live in central NJ with still high real estate market, but plenty of foreclosure and short sale.
There is a house listed for 509k in short sale. It seems to be in good condition in a nice area. So I was wondering how low offer should I put on this house?

If you are going to pay a short sale house who is going to buy your real estate agent?

Another advice that I’d like to read. If you looking for a short sale house that price is decreasing the prices from a couple a months ago 290k to current 240k , what should I assume? It is possible that the price to start bid is still going down in those crisis days?

How long does it usually take for a short sale to go through once the seller has accepted my offer?

I don’t need an exact time-frame just an approximation of an average short sale. As of today it has been 78 days and we have not heard anything from the lender at all?

We know that the offer is not lost, nor have they accepted another as the seller’s agent just talked to the bank this morning. We are just waiting for the lender to get a move on this.