I don't think there's a museum at the Velodrome d'Hiver site (the building itself doesn't exist anymore). There's a monument there : https://fr.wikipedia.org/wiki/Place_des_Martyrs-Juifs-du-V%C3%A9lodrome-d%27Hiver
This is a public space where you can go as you wish. On certain occasion, there might be public ceremonies taking place here, notably around the end of july which is the date where the actual 'rafle' took place.
There's a memorial in Drancy : http://drancy.memorialdelashoah.org/en/the-drancy-memorial/presentation.html I think it is managed by the Memorial de la Shoah foundation. The website gives some details on how to plan your visit : http://drancy.memorialdelashoah.org/en/the-drancy-memorial/planning-your-visit.html The website might help you getting more information on what to expect in this memorial.
Notice that the Memorial de la Shoah foundation also have a museum space inside Paris : http://www.memorialdelashoah.org/en/the-memorial/planning-your-visit.html
In addition, you can also have a guided visit at the Bobigny train station from where several convoy left for death camps : https://exploreparis.com/en/111-bobigny-deportation-center-station.html