There are multiple routes between Sesriem and Windhoek. This one first lead through the Naukluft Berge where there are water springs all year round and later over the Spreetshoogte Pass, with a 22% slope (!) the second steepest pass in Namibia.
The first part of the route as far as Solitaire is quite a good dirt road. At the Spreetshoogte Pass the steepest parts are well made with cobble stones. After the pass the road gets worse with lots of loose gravel.
There are some lodges & camp sites along the route ( see roadbook. Many of them are quite far off the main route. Although most of the area is fenced off, wild camping is no problem.
In Sesriem and Solitaire there are simple shops. In Solitaire there is a good bakery. You can get water at the accommodation options and farms along the way (see roadbook).