As you mentioned, Bug/Issue trackers are a huge help in keeping everything on track. As for prioritizing features, this should be left to the community. Voting is the best way to prioritize. Enable voting in the bug tracker and allow users as well as contributors to vote on the highest priority features.
Other tools to consider, GIT/GitHub as a version control system. This is an easy way to share the source code and allow others to work on the code base. Also, consider a integration server such as Team City or Cruise Control. If you automate your builds, you can publish a new build every time there is a check-in. This will allow users to immediately consume a new feature or change without waiting for a formal release or building the source themselves.