after posting some information about the roads in Kaokoland, I recived some messages with additional questions, so I thought it might be an good idea to put up a separate post. Keep in mind that these conditions might have changed - always speak to people before using an unknown road!
Preparations: GPS, one standard (good in cities) and one with Tracks4Africa. 3 different maps, one for South Africa, Tracks4Africa map for Namibia and a map just for Kaokoland.
Extra 40 liters of diesel on the roof, 60 liters of water, food for 4-5 days. 2 spare tires, repair kit, winch in the front, sand tracks.
The roads, I will not name them all as the B-roads in Namibia are very good:
South Africa: Tarmac all the way from Pretoria to Upington, pretty boring road.
Ariamsvlei (boarder post) to Grunau via B3 - tarmac, very good condition.
Grunau - Seeheim via C12 - gravel, good condition - very dusty! The C12 split just before Seeheim, you can drive the old road which passes Seeheim. Be aware that that road (approx 20-30 km) is very bad in places. Quite fun to drive though. Drive the new streach if you are in a hurry or just want a nice and gentle drive.
Goageb - Sesriem via C14, D425, C13, C27. All gravel, C-roads are quite easy to drive. D425 is very hilly and steep, but no problem with any 4x4.
Sesriem-Windhoek via C27, C19, D1275 (Spreetshoogte Pass). Gravel (off course), good conditions, some corrugations between Sesriem and Solitaire. There was a lot of graders out working so the conditions might have improved. D1275 is in good condition but Spreetshoogte Pass is very, very steep - no trailers or caravans. Use your engine brake going downhill so you don't overheat the brakes.
Windhoek - Uis via B1, B2, C36. Not much to say, B-roads are paved and in good condition. A lot of road works going onbetween Windhoek and Okahandja. C36 in gravel and in good condition.
Uis-Twyfelfontein, C35, D2612. All roads in good condition, loads of tourists in the area so you can use an normal sedan car. Don't venture out on any other road though.
Twyfelfontein-Sesfontein, C39, C43. Roads are getting a bit worse, but no problem.
Sesfontein - Purros, D3707. Fuel up in Sesfontein as there's no fuel stations until Opuwo. You can get fuel in small quantities in small villages, but at a very high price and fuel contamination is a real risk. Road is twisty, very rocky at some spots and a lot of very sandy riverbed crossing. You really need a 4x4 here.
Purros - Orupembe, D3707.
Finding the road to Orupembe can be a challange, there a a lot of roads leading over the riverbed. Start from Purros town "centre" and then go straight west over the riverbed. This strech of road is ok, wide gravel road with some (very bad) corrugations, just a few tight spots. Depending on the road conditions, allow everything between 3-6 hours.
The road (D3707) starts out as quite a good road, but deteriorate after a few kilometers. This is a strict 4x4 trail, many riverbed crossings with sand and/or large stones. Few places with mud as well, watch out! At one point the road was almost washed away, you need to be a confident and good driver to make it trough (or have a good car). Rest of the road is slow and rocky, and remains so all the way to Oruwanje. After Oruwanje, the road to Opuwo is ok. Total time can be everything from 6-8 hours.
Opuwo - Epupa Falls
Good gravel road, lots of cattle and people on the road, watch out! Allow about 3 hours.
Epupa Falls - Ruacana via D3700
I was going to drive this road as it was upgraded a few years ago, but apparently the rain season had made it to an mud pit. I was strongly advised not to use it and instead I drove back to Opuwo.
Swakopmund - Windhoek via C28
Instead of using B2, I drove C28 which is a shorter route but takes more time. Very steep in places, no trailers or caravans! The road conditions are good for the most time, but in a few places it's quite rocky with large stones. Wouldn't drive this road without an 4x4. Took me about 6 hours, including breakes.