I've not been to Botswana, so I'm not sure exactly what kind of circumstances you will see on your safari, but when I went on safari in Kenya and Tanzania, I had a 5DII with 24-105 and 7D with 100-400 90% of the time. I felt that covered almost all situations I needed to cover, including a close encounter with a cheetah that jumped on our truck:
This shot was taken right after i ducked in the truck when the cheetah jumped on at exactly the same place I was standing and taking photos. I was able to quickly put down my 7D and grab my 5DII with 24-105 lens on it, in order to get this wide angle shot while the cheetah stood there for about 5 seconds.
I also brought the 17-40 i had at the time and used it with the 5DII for some wide landscape shots. If you've read the other threads, you'll see that its unanimous that you should bring at least 2 bodies. That way you have some insurance if one craps out, and also you won't need to constantly change lenses, which may make you miss shots and increases the chances of dust getting into the sensor. So definitely bring both your 5DII and 7D.
As for lenses, I would bring your 24-70, 70-200, and 2x extender. The tokina won't add much since it's only for your 7D and you will get wide enough with your 24-70 on the 5DII. You could also bring your 50 1.8 in case you need something for low-light situations. You may also want to think about renting or buying either the 100-400 or a 300 or 400 prime that you can use with your 2x. Again, this somewhat depends on how close your car can get to the animals on the safari. For me, I found myself at 400mm on the 7D a lot, and did feel that more reach would have been even better in certain situations. If you buy a used lens, you could probably sell it when you return for the same price, or just a bit less.
The flashes will not be that useful so you can leave those home, unless you plan to do a night safari. If you do a night safari, I read that a flash extender is helpful.
I didn't find a tripod or monopod necessary in the car, but I used a bean bag all the time. Ask your safari outfitter if they have bean bags in the trucks. Many do. I did bring my own Omni pod and loved it. it attaches on to the tripod column of the lens and made it easy for me to quickly move from place to place in the car. I also brought a tripod, but that was mainly used when I was at the lodge or camp and wanted to take photos my wife and me together.
As for luggage, do try to pack as light as possible. I had a med size duffle for my clothes and tripod, and carried my camera bodies and lenses in a backpack that I kept with me at all time. Some of the local airlines will be sticklers for luggage weight restrictions, but it usually just take some extra money to resolve. I also wore a photo vest that is able to carry some stuff on my body, in case i needed to lighten the weight of my bag or backpack.
Hope this helps get you started. There's a ton of information out there and I could go on for hours on what gear to bring. The research and gear shopping was actually part of the fun for me. Good luck and enjoy! By the way, here's an example of the type of shots you can look forward to