Currency & Insurance
In South Africa, you will be able to draw cash from ATM's so I do not recommend exchanging money for South Africa. It is to your benefit to rather draw cash from an ATM as and when you need to. Most places in South Africa also accept credit card.
For purchases of gifts in Vic Falls or Tanzania, I recommend that you have US$ cash. I suggest having about $500 in US$ cash to travel with for your entire trip, over and above the $300 for visas. Be sure to have a good selection of smaller bills.
For travel insurance, please contact Travel Guard. You can acquire the insurance directly on-line with the following insurance brokers:
Medical Evacuation: www.globalrescue.com
Trip Cancellation: www.huntandtravel.com or www.travelguard.com
Trophy Replacement: www.lechnerstauffer.com