There will probably be two or three visas required BUT you just do them on arrival usually on the ship. Ghana, Gambia and South Africa I know require visas but nothing you need to do ahead of time.

Pretty much yellow fever is not required these days unless you have been in an endemic country. We will not have been to an endemic country. Things constantly change of course and we will be advised if yellow fever is required. My instinct is that it will not be required.

In the past nothing special to be concerned about on this cruise.