At first over the Gamsberg Pass down to the Namib desert and then straight across it. The route across the desert is quite monotone but also fascinating at the same time. The road is often rough and on the last (long) stretch there is no water at all.
The road over the Gamsberg Pass has lots of soft gravel. It is quite demanding even downhill with all the short climbs. The road through the Park is not bad but not really good either. There is quite some traffic here.
Along the first part, there quite some guestfarms. Once inside the park there are only 2 simple campsites (no water). Officially you'd need a permit to camp here... Wild camping is never a problem, but other then at the camp sites there is no shade in the park.
Buy all supplies in Windhoek (or Swakopmund). Along the first part there are some farms where you can get water. Once inside the park, there is no water at all anymore (also no water at the camp sites!). Take enough water for that stretch as it is also very hot.