Great advice, kipper.
Big book shops usually have detailed maps of parks but I agree they re a bit hard to find. With GPS you can not get lost anymore but please remember that GPS will not show you which areas should be avoided for security reasons. Remote borders are often used for illegal transfers. It always helps to speak to locals before leaving for such areas.
It is always a good advice to share your itinerary with someone and ask them to search for you if you do not report as arranged. Then again, please consider that you might not have reception for your mobile at the planned destination, so do not trigger off a search just because you said you will send an SMS on arrival and when you get there, there is no reception.
A good jeep will get you through nearly any terrain but it makes sense to have some experience. Do not test your (or the cars) abilities if there is no help in sight. To save fuel (for the sake of the environment and your budget) you might want to switch off 4-wheel drive on normal roads even if not asphalted. The reduction of fuel consumption is significant.
Your jeep might have a differential lock on the wheel. Keeping the differential lock on all the time produces enormous noise and wears off tires extremely. Hence it is normally kept off. Keep this in mind when approaching wildlife. I once got myself stuck in a little puddle just because I wanted to go one meter forward for a great photo of a lion. The only way to get out of the puddle was to get out of the car to activate the differential lock. The lion watched me very skeptically as I was fiddling about with the wheel. Not a situation I would like to go through again.
I fully agree with Kipper that you are best off with a driver that has local knowledge. Most drivers are experienced and know where to look for wildlife. Whilst the driver will take you wherever you wish, you can keep your head out of the roof and enjoy the atmosphere rather than having to worry about poor road conditions. He can also help with negotiations with locals if you do not speak the local language but keep in mind that he might add his own profit into the bargain.
The only advantage I see in rooftop tents is a better view in the morning and maybe less insects trying to share your bed.
We tend to read signs like "keep your rubbish in the car" as a pure advice not to litter the environment. Of course this applies as well but first time visitors will be surprised how many insects and small animals are keen to tear anything apart in order to get to the content. A plastic bag in the tent that smells of food will definitely attract animals and on your return you might end up with your tent torn to pieces. Even in New Zealand I once woke up in the night as an opossum tried to rip a hole in my tent to get to my rubbish. Many animals are used to humans and will not feel threatened by a simple "ksst, kssst". I had to get out of the tent and approach the opossum to convince it to let go of my tent. Replace the opossum with a hyena and you have a problem
If you are looking for cheap accommodation, you might also speak to game wardens as you enter the parks. In many parks the Wildlife Service has vacant cottages for wardens or even rooms for visitors that can be rented. I always enjoy these places because you get a chance to spend the whole evening to chat with the wardens and learn a lot from them.