Communication with friends/family at home or with your travelling companions is easy with a Cell phone that has a SIM card. Check your cell phone before leaving home on whether or not is has a SIM card and if it does then you need to purchase another one for the country that you will be visiting.
These are inexpensive and purchased when you buy Air Time at the place where you will be staying. I usually obtain one for South Africa and another for Namibia. In the meantime before these are purchased I leave my SIM card for home in my phone and reinsert it when I arrive back into Canada.
When you arrive at your destination you will be able to contact family/friends at home, taxis in local area or for an Emergency.
To charge any batteries - phone, camera etc. you will require an Adapter for that country. South Africa has a three prong rounded pin. Namibia is also three pronged rounded pin. Zambia uses a three prong flat pin the same as UK. You will require three or four Adapters for hairdryers, curling irons, battery chargers and computers for the specific countries.
Bush Camps have limited outlets for charging batteries and in some remote areas batteries have to be charged at a communal area such as in a lounge.
Computers - some accommodate SIM cards otherwise you may have to pay for Roaming services or pay for WiFi at your destination.
Computers can be great to have however, they add extra weight along with all your camera gear. The airlines make up their own rules but are VERY specific on what you are allowed to carry on board! On the smaller planes sometimes it is only possible to take ONE case with you on board which then becomes a big decision as to what goes on and what is checked especially with multiple camera lenses.
If you plan to take your computer for only downloading photos it would be better to invest in taking sufficient memory cards with you to avoid the unnecessary weight. Taking along something like an Epson viewer is also another way to download your photos but don't delete them from your memory card until absolutely sure you need the extra memory!
IPads are becoming more popular now and much lighter, although not as good for downloading high resolution photos which has caused serious problems for some.