Also cant quite see how i can expot runs ive done as gpx files.
Start a run (or navigation) activity, go to options -> Navigation -> Activities
Select an activity from the list and you can choose 'Go' to navigate it (or 'Back to start' to go back to the starting point I guess) and Map/Elevation plot to view the course-map and elevation..
You can't do it from the activity history itself...
Besides navigating an old activity directly on the watch you can create course from the activity and then use that. You must do that in Garmin Connect Web. Go to the activity, click cog wheel in upper right corner and select "Save as Course". Then you can send that course to the watch and navigate it.