I am not qualified to give you advice even though I was raised in Napa. However, I do know the best real estate broker in town to call. He is the owner and broker at BRiX Real Estate Inc. and I know he would be happy to help answer any questions whether you planned to use him or not. His name is Dana Lopez.. His number is (707)225-1844 and his website is brixrealestate.com where you can also do a home search for homes in Napa on your own. His email is email@example.com.
Hope you find what you're looking for!