Just got back from Namibia and South Africa.
If you're going to visit South Africa too, take South African Rand with you to Namibia. It is accepted like local currency, but they'll give you change in Namibian Rand. Before you leave Namibia, make sure you use it all or change it to SA Rand or other currencies because you may have tough time finding an outlet taking Namibian Rand once you left.
ATM is available in most towns I stopped at. But make sure you have a Visa ATM card. Finding an ATM that takes MC could be as tough as spotting a leopard in Etosha.
Northern Namibia got some heavy rain storms in November so if you're going there soon, best to take malaria pills with you.
