Martin, On the Winterization question, it is the seller's responsibility to deliver the property in the same condition as it was shown when the agreement to purchase was made. So like others have said, it is the seller's responsibility.
Short sales don't need to be a nightmare. They do involve a bit more paperwork, and the seller's lender will ask for some documents again, and again, but this is due to the fact they that will generally only work with docs that are 60 days old, or less. If you are working with a listing agent that has experience in short sales the process should go well. Most times the delays come from inexperience, not having all the required documents upfront, and not having experience in working the the seller's lender.
If all goes well, getting the third party approval can be as quick at 45 days.