Can we drive thru the safari with the doors off the jeep?

Yes

I would say yes, We were there a month ago and I never seen any bison. They were far enough away not to be close enough to our vehicle

Once you get to a certain area where the Bisons are, there is a sign telling you to shut your windows and to not feed them so i am not sure about that!

I drive a convertible. They told me to not stop around or feed the longhorns or bison.