hi,
i think you got the focus as close as you are going to useing that method..with regards to the appature...trial and error is the best way to get it right..but having said that i would be leaning towards a larger appeture setting to let as much light in in those 10 seconds..get the exposure time as long as you can before you start to get trailing(streaky looking stars)..have you tried photagraphing the planets??saturn or jupiter....much easier useing the method you are useing...keep it up
