You are going to have the time of your life!!!!!!!
I went on 10 day safari in Tanzania in 1994. Hotels are very first class given how far away one is from everything. I can't help you with anything on warfarin as I'm tissue, and the trip was long before my stenosis acted up. Remember, my comments are from an experience over 10 years old so much may have changed. Also, you don't mention if you are going on business or if you will be caravanning on photo safari. I will assume the latter.
We were advised to take our own syringes in case any injections were needed at a hospital for anything. Needles and AIDS type precaution. Can't imagine being unconscious and remembering first to tell someone, hey, don't forget my needles! But anyway.
Do not swim in any of the swimming pools. There is a bacteria which can infect the eyes and cause blindness (quite prevalent in Africa) and while a simple regimine of antibiotics will cure it stateside, not worth the risk. We had a fellow traveler who did go swimming, come down with it and was lucky to have a keen doctor to figure out what was going on. Obviously, do not drink their water either.
Be sure to do the malaria pills or whatever they give now. We brought along some "sting-ese" and were glad we did when one evening in the Serengetti we were late out of the park and were heavily bitten by tse-tse flies. Nasty little buggers. Sting-ease helped calm the little bites.
Photography. We were told to take an old men's wool/nylon type sock and fill it with plastic pellets and sew it up tight (about 5-6 inches of it). With this, we could hang it over the top edge of the window to steady the telephoto lens. VERY helpful!! You can also buy mini-tripods with velcro straps on them -- REI used to carry them-- and they are great handholds for steadying the camera also.
If you don't have the camera you wished you had for this trip, bite the bullet -- buck up and go out and buy it NOW and practice with it for awhile. You will never regret it. The picture opportunities are phenomenal. When we arrived, we went to the hotel gift shop and bought the wildlife guide for the area. Very fun to have the animals pictured and identified so you knew what you were "shooting".
We did spend several nights in a tent...a very solid tent!! But the bugs were so noisy and the animals so close that I got a bad case of the heebie jeebies. I found (and several other people with us used my idea and were able to sleep at last) that by putting socks over my hands and feet the creepy crawlie feelings were somehow psychologically protected and I was able to relax and sleep.
Well that should be enough!!! Sorry I went on and on. Oh! Such a wonderful trip to be doing!!! How exciting!!
Marguerite