@PARA45
My answer will not answer all your exact questions, but here it is, hoping you will get a rought idea:
On my first hunt for PG, I used camp rifle steyr 375 H&H. And all went down. My first shot on Oryx was bad, so Oryx was wonded but tracked on spoor and I took second shot. The rest was one shot kills from warthog to kudu.
Ammo used on that hunt was local PMP.
So, for PG, I dont see much philosophy with 375 H&H, about this and that.
My second PG hunt, was again with camp gun, but this time mauser 98 in 300 H&H.
All went down, PMP, and PPU if I remember correctly, including zebra stallion, of 400 kg mass. (or whatever mass is for Hartmann Zebra stallion)
For DG, i have no experience, but I trusted the collective knoledge of this forum, and since then I bought zkk 602 in 375 H&H, and for Africa prepared swift A frames, 300 grains, hoping to go after buffalo. (when my timing permits)
Bottom line is this:
375 H&H by modern standards has moderate velocity, and for this reason many of the old fashion, low tech bullets for plains game will work excellent. For DG, get yourself prepared by zeroing and having some of the premium bullets.