If cost/capital expenditure is on IPP, then all good.
Consumer would pay for kWh used at competitive rates.
Not really, new nuclear is not cost competitive, and a lot of the cost will come from borrowing.

Nuclear has a capital expenditure of $3.7bn for 2.2GW best-case. South Africa is going to look at at least 1GW options, so ~$2bn best-case, worst-case around $3.6bn in capital that needs to be paid off within 20 years, meanwhile it will gather interest during any construction delay. With IPP, you will not get government levels of interest.
Nuclear is mostly developed countries:

South Africa will not get this level of interest, and most IPP will not even come close. Do you think nuclear will be cost competitive based on that? Note that most nuclear in the world until very recently has had state subsidies, that includes France and US.
And you can't really build small scale, quick nuclear, you can't decide you only want a 200MW build now and then keep doing that, it will be a lot more expensive than contracting for 2GW in one go.
Solar thermal towers you contract 50-200MW and you can keep contracting it one after the other when the first one finishes. It makes it a lot easier for a country to budget, and it's going to start paying off its debt a lot quicker. For South Africa, you'll get a lot of favorable loans from the world bank for renewable, and so will IPPs if there is a guaranteed contract in place.