Hi there, i've not shot in velodrome before but I did volunteer at the Junior Track World Championships last year, helping with the press and photographers, and will be volunteering in the velodrome at the Commonwealth Games next month.
The tip about only kneeling on one knee is a good one. We had one photographer who thought that rule didn't apply to him and was seen at one point lying on the apron to get a real low vantage point. The venue manager very quickly told him that that wasn't permitted. The other rule that we told the photographers was that they had to be within one arms length of the inside boards. This was to ensure that they didn't get too close to the cyclists. This may different at each velodrome though.
Most of the photographers had a 70-200, a 300 and I think it was a 16-35 as their lenses of choice. Most also has flashguns as well but they did ask whether or not they were allowed, so each venue or competition must have different rules on the use of flash.
Look out for some 'alternative' viewpoints. The Glasgow velodrome has a high level walkway that is used to gain access to the ventilation equipment etc. I'm pretty sure that we'll have some cameras up there during the Commonwealth games to give a different perspective on the event.