Hey no worries, if you don't ask how will you know?
OK so most safari parks have nice wide roads through the park that will allow at least 2 vehicles abreast so you should never really be stuck behind someone unless the park is jam packed full, then traffic flow can get a bit stilted, particularly if an exhibit is predomenantly on one side of the vehicles say. So at WMSP the Indian Rhino are in a separate paddock within the 'asian' zone area that is on the right side as you drive through, although the paddock is large, if something interesting is going on then people tend to stop and watch - no problem with that but it can be frustrating if you are just out of watching range and missing out. Your options are to sit tight and shuffle up as other cars move on or drive around to the next section maybe and enjoy that, returning to the one you missed later. You can enter the safari drive as many times as you like once you are in and paid, they have a designated route around to aid traffic flow (so they are all one way in my experience, no two way traffic flow). The Cheetah at WMSP are on the left hand side of the road as you drive around, you get a sign telling you what's coming up next and with a bit of experience you can position your vehicle well. I have got some decent photos of the cheetah despite them being behind a fence.
Now, safari park etiquette, if indeed it exists, may say that you don't hog the animal and let others enjoy it too - difficult if they are being very interesting and photogenic, it's up to you - I say you've paid your money as much as anyone else and as long as you are not deliberately blocking someone then spend as long as you like watching the animals.
I have been the WMSP in the off peak season when it's less busy - I prefer that, especially in with the african hunting dogs - they are magnificent - so I tucked the car to the side of the road and switched the engine off and spent a good hour almost just enjoying watching them do their thing - no one else drove through and at one point the keeper trundled across just to make sure I hadn't broken down - no problem with spending time at any exhibit.
In closing this essay, I'd say the safari drive takes at least an hour if you want to see eveerything and for me at least 2 hours to do it justice. The park advise either getting there for when it opens and doing the drive bit straight away (good advice actually) or going around the walking part first if you get there around 11am - choice is yours - the walking bit is an odd mix of a theme park and a small zoo - the small nocturnal house was a great surprise as it contains an Aye-Aye (frustratingly difficult to photograph) as well as free flying fruit bats. Sealions with shows a few times a day, a lemur wood walk through, Hippos in a lake at the very end of the rides part and an african village with oodles of meerkats.
The drive is excellent for me - the Leopards are unfortunately now in an enclosure at the start of the drive and as such very hard to see - their old enclosure that was in the walk round part now has lemurs - I'd prefer to still get closer access to the cats but understand the issues with the unsuitability of the enclosure for them - hence the change.
Either way - go and enjoy it, I don't think you'll be dissapointed