The time It takes for a bank to get you out of your home will vary. It really depends on how aggressive the bank is. Some people have been foreclosed on after missing 3 or 4 payments while others haven't made a payment in 2 or 3 years and are still in there home.
The best way to estimate your homes "market value" is to find out what homes similar to yours are selling for in your area.
Interest rates are very low and most sellers are willing to negotiate their selling price; so this is a good market for buyers.
There is no doubt you will get less buyers viewing your home in the colder months, but if your house priced right and well marketed, you should still be able to generate a good amount of interest in your property.
How much an agent charges should have direct link to how much exposure your home will receive. The more people that see your house the better your chances are of selling it. Find out exactly how that agent will market and advertise your home and how he/she will get your property seen by potential buyers.