How long does a short sale take and how often do they go through?

The house we loved apparently is in financial trouble. We did not know this until after we put an offer in. We put in a fair offer and were not trying to lowball. Apparently there is now a local bank and Fanny Mae involved in the process. We have left our offer up even though it is expired now. From what I have read the bank will do an appraisal and if it is near our offer they may approve it. Is this correct? We are not in a hurry to move so we don’t mind waiting it out. I am just curious if we need to do anything or keep an eye out for somemthing. I have read that it is not a fun process and realtors don’t really like it and it does seem like our realtor would rather point us in the direction of another home but this is the home we want. So I would like to know how long are we looking at in general on this? Do these things go through? If it does not get approved how long is it before the home is listed as foreclosed and what can we do to try to get it at that point? It seems the people that own it may very well owe more than the home is worth and we are not willing to take on that burden, but if we can get it for the appraised value or near that we would be very interested. Does a foreclosed home force you to pick up the exact amount of debt the previous owner had on the home?

Edit to add- The home listing makes no mention of any of the terms that I see should be there for a possible short sale. I am curious if they update the listing in the near future what would happen if our offer is higher but expired vs a lower offer that is not expired? I would assume that the bank would want the higher offer but does the fact that it has expired make them go towards the non expired offer?