Simon,
Think you should speak to Ian Anderson really, but my input for now is that there are the Track Laps on the Friday night and the Club/Parade Laps on the Saturday morning (not sure of precise times off the top of my head).
Other things to do/see (but I'm sure you probably did these anyway) - all the paddocks, the pits (if you can get in), the village: shops/market stalls/entertainment etc. There is an auction but think its not cheap to get in there. There's also the museum, which you pay for separately if you want to (I haven't actually been in the main part, only the front/cafe).
Cheers,
Max