No doubt it's a lovely drive down (I did round trips between Durban and Joburg every other weekend for almost two years while working in Johannesburg). I would say hitting the freeway for the first time off a plane and being unprepared may be unnerving if you're not an assertive driver.
It's entirely customary to find someone driving up your backside while taking phone calls, indicating is not expected and if you're one of the critics of middle lane drivers here in the UK then you may be a convert in SA because slow lanes get damaged from road freight and the outside lane is an express train of vehicles (including taxis) mostly travelling at speeds far in excess of the limit.
There's also been a long history of road deaths on that route:
...however it is very scenic and I can't imagine there's many nicer ways of arriving in Durban for Comrades than passing Pietermaritzburg and then counting down the names of the various hills flying by before you arrive at the coast so if you're going to go for it then I recommend probably worth finding a quiet time to leave and just ensuring you're well rested before you do.
I think creating a Bobs Book type thing with photos and experiences would be a fun exercise for anyone however Fido & SD would have the hints and tips to make it an interesting read for newbies and greens alike (wouldn't add Maccie D's as mandatory race nutrition)
Lowrez - almost didn't get past line 2 where you said "weekly leg massages"