navit is still very alpha and navigation through addresses doesn't work very well, as far as i know. recent svn are really slow on n810, i think that navit's guru in the forum, gerritv or dwould, could build n810 optimized navit packages, i can't do it myself. gerritv is on holiday with no connectivity, so the only one that can help us is dwould, unless you can do it yourself.
The latest optimized build wich i'm aware of is the one you can download from gerritv's blog: http://tech.visser-scully.ca/
post #280 in this thread explain how to route through two points of known coordinates.
if you need reliable navigation right now i think you better use maemo mapper or buy a temporary wayfinder license