Since 230V is in the range 100-240V, you do not need a transformer. You will probably need an adapter. Botswana doesn't seem to have a standard; can you find out what kind of plugs are in your hotel, or the business you're visiting?
I would suggest bringing at least one adapter labeled Africa and a British one, but consider a universal adapter so you can ...
There are a couple of campsites near Ghanzi which is about halfway between Gaborone and Windhoek.
El Fari Bushcamp
Grassland Bushman Lodge
I can recommend Thakadu which is basic but clean and has a nice bar and restaurant with a waterhole nearby.
The camp site of Tautona Lodge is fine too but it is a bit far away ...
Botswana is open for tourists, you can visit with a valid passport up to 90 days total within a calendar year. Notice that leaving the country and coming back does not renew the 90 days period.
There is no need for for sufficient funds proof as far as I experienced, for myself or for visitors.
Valid passport (Botswana and South Africa) must have:
Recently came back from the trip. Ganzi is an option for better accomedation (more options), and we did stayed there on the way back from Maun. Unfortunately, it was too far from Gaborone for us (670 Km), and added another 100 Km to the trip.
We did found a place to stay in closer to the middle:
Kang village which is 420 Km from Gaborone and about 400 Km ...
Here's a canonical reference for Peter Green's answer (sorry, too long for a comment).
Botswana uses Type D, Type G and Type M sockets. See:
noting the panel to the right contains 'Botswana' in each case.
These are specified here:
Not necessarily comprehensive but perhaps 'a start', from Service Wi-Fi Space where there is also a map:
In a Comment OP has reported:
Europa did have the best internet in town for a while, but something happened and now Macs can't connect. Mugg and Bean is a SA chain and they give you a voucher with one hour of very slow internet.
Bull & ...
The Univisa program is inactive, get regular visa for both countries.
Consular info for Zambia from gov.uk
The Kaza UNIVISA is temporarily suspended until further notice. If you’re planning to travel between Livingstone, Zambia and Victoria Falls, Zimbabwe, you’ll need to apply for a visa for each of the countries.
Same for Zimbabwe
The UNIVISA ...
You don't need a transformer, but you will need one or more plug adaptors. From some googling it seems that Botswana uses a mixture of British 5A, 13A and 15A plug types.
Unfortunately in my googling I failed to find a source of adaptors for connecting American plugs to 5A and 15A BS546 sockets that I was happy to recommend. The only ones I found had ...