Good morning Cbisio!
I am happy to answer all three of your questions. The lowest average price per square foot for all single family homes (detached) in the City of Sonoma over the last 15 months was $ 272.00. If your home was 1000 square feet in size it should list for an average price of $ 272,000. The month reflected here is January of 2012. Cbisio, I have no idea where your home is located, how it is situated on your street, what size it is, how many bedrooms and bathrooms it offers, it's physical condition, etc. In other words my answer is oversimplified. For an accurate answer to your first question I would need more information.
When selling your home you cannot rely on a percentage amount for what you originally bought it for as a rule of thumb. After you sell your home you could arrive at this figure but not prior. Why? Because the market value of your home rests on multiple variables which you can change such as physical condition and features and some of those you cannot, i.e. neighborhood, size of home, and current market supply and demand.
Can you rent your home out? You bet! Sonoma County is experiencing a strong rental market and as long as your home is in good shape, functions well, and is priced correctly will rent quickly. If this is a route you are interested in let me know. I have prior property management experience and can steer you in the right direction.
Cbisio, call me and we can make an appointment to meet at your beautiful home. My cell is (707) 481-5506. You can call me any time any day. Then we can sit down and chat about all of your options and I can provide you with a much closer estimation of your homes current market valuation.