Todd:
The preceding posts contain excellent advice.
I have hunted buff exclusively in Zim. Twice in Matetsi unit 3, Twice in Chirisa, once in Chete and once in Sijarrara.
My last buff hunt was 2011 in Chirisa. It is my favorite place to hunt buff and is an HHK concession.
Saw the most buff in Chirisa, but it depends on the time of the year. June-July are good months to go and because of that, June-August hunts sell the quickest.
A bull goes for ~$2,500 in Zim, plus dailies, which vary from $900 to $1,250, depending on the area and outfitter.
You have allotted plenty of time to hunt your buff. if you go to Zim, why not add a tuskless cow elephant? Great fun to hunt and quite reasonable. Usually about $2,500.
A day is all you need to see Vic Falls. The Victoria Falls Hotel is a classic venue to stay. The Royal Livingstone on the Zambia side of the falls is very nice and more like a resort.
I agree that you should go to the DSC show to book your hunt. Many of the prime hunts are sold there and are therefore gone by the time of the SCI show a month later.
