BuddyPress.org

“Is hard coding the way to get the MAIN nav with CATEGORIES as links?”

No, it’s the exact same way as building a nav bar with pages in a WP theme. Except you use the categories list function.

Tip: start with buddymatic. Find one of the magazine-style Thematic skins and use that with it, changing the style.css so it uses buddymatic templates instead of thematic. I’d recommend Commune That will get you most of the way there, in maybe a half hour.