The currency in South Africa is the rand. MasterCard and Visa are accepted most places and travelers checks in US dollars are valid at banks, hotels, restaurants and a few shops. Unfortunately, money scams abound in South Africa and many of them are through the ATMs. Most hotels will change money for you or have an onsite ATM that is safe to use.
Your passport must be valid for at least 30 days after the intended date of departure and must have at least two blank pages for entry stamps and visas. If you do not have two blank pages in your passport, you will be denied entry to South Africa and sent home.