You can get our build release schedules from the Community Events linkon the left hand side navigation Community Home:http://sqlnavigator.inside.quest.com/community_events.jspa. The nextbuild will be available next week.
You can install the current Beta build as the preferences will not be lost when you upgrade the next Beta Build.
The first time you run the new release, you should get the prompt giving you an option to migrate your preferences (as Side by Side support has been added to SQL Nav for a while).
Regarding your preference settings and projects info in 5.5.1, you can use your Profile Manager utility (Backup/Restore) which can be found under Start->All Programs->Quest Software->SQL Navigatorxx.
Please let us know if you would need any further assistance or info.
Thanks from all of us for working with our Dev team on SQL Navigator.