I didn't go to Torra Bay from Twyfelfontein so can't comment on this route.
However I can recommend the alternative route we took between Twyfelfontein and Swakop as one of the most spectacular day's drive I've ever done. Geological oddities, moonscapes, Welwichia plants, the massive Brandberg viewed around 270 deg and all on a very well maintained, hard base, gravel road that was safer to drive on than most of the crappily maintained unsealed roads in my native Australia. From Swakop turn R onto D2303 @ the 105 Mile (or 100 Mile depending on your map) about 70 km past Cape Cross. Stay on this and it becomes D2342 and sweeps round the W edge of the Brandberg. Turn L onto C35 and you're back on the standard route between Henties Bay and Khorixas via Uis. I tried more back roads N of Uis for more great views and took D2612 up towards Twyfelfontein instead of going via Khorixas. All good. Its a longish but easily doable day. Get up early and see Twyfelfontein as the afternoon cools. Check out the route on Google Earth to see the folded geology. In Layers/Gallery turn on Traks4Africa - a great resource.
For a camp handy to Twyfelfontein I can highly recommend Camp Xaragu which is just N off C39 near the S turnoff for Twyfelfontein. Its cheap, got neat, SHADED campsites, cute kero lantern-lit amenity blocks and, incredibly, had an ostrich, a bok and a young kudu just wandering around AND a pet baby meerkat that adopted the family after we gave it an egg.
The above trip was in early Dec 07 so heavy rain since then may have changed the road conditions, of course.