I believe that the navigation bar, like the current website, should have many sections immediately accessible, without drop-down lists (and I'm not sure this works on touchscreens).
Downloading is primarily important for end users, since there's "nothing to do" without the program. Secondly, the documentation and wiki are important for studying, users will return to them repeatedly. And the forum and bug-tracker will help with complex issues.
Also, the navigation bar will immediately show how large the FP community is ))