I've done it CPT once and JNB twice.
My husband flies it alot and yes, NR's get tossed off in DKR with some frequency. usually S4 and they fly in "packs" of 3-6 family memebrs so they all get off together. It's a bit odd.

Shots--well, technically, you are required to have yellow fever if you get off in Senegal and enter SA but I've never had anyone ask me for mine and I've split legs thru DKR.
I will look at the listings--which dates, please? What's your status/priority/seniority etc--happy to keep an eye on # and pm info.
If the seats show that many you should have no trouble. They do leave empty seats for cargo weight/balance but not that many?
taxes for DKR are high--total for RT was around $140 for employees. I'll check my most recent and get back with exact. I've done both the ATL and JFK routes. Hope that helps!