Our group leader was Often, of whom I cannot speak highly enough. I've been on a lot of trips and had good leaders, but Often is the best yet! He was friendly, helpful, cheerful, and managed to get along with everyone without ever being imposing. His awareness of the group's mood was excellent - he always noticed if someone was feeling a bit ill or sad for some reason and responded. Not to mention the fact he could do everything from fix the truck to bake a cake on an open fire! There's no end to this guy's talents!
But I also have to mention the cook, Benard, and the driver, Nebert. The three men made a great team and all were the most helpful, friendly and professional guides you could wish to meet. They worked incredibly hard and their love for their jobs came across in everything they did.
If you're worried about your fitness for the gorilla trekking, don't let it stop you going. I was in a group with a lady who'd had both knees replaced and she made it! The pace is slow because the undergrowth is so thick, so don't worry about being superfit, though of course it's a good incentive to get down the gym! The worst thing on the trek were the stinging nettles - wear thick trousers, a long sleeved shirt, proper walking boots with good thick socks, and gardening gloves. They provide you with sticks so don't worry about walking poles. The rest of the trip is well within the capabilities of most people.
Take a couple of books as there are some long drives, though the truck does have a library which you can use. Pack as lightly as you can. Don't put on clean clothes before a long truck drive - you'll get covered in dust. It's worth taking several smaller bags within your main bag and dividing up your things into groups e.g. wash kit, gorilla trek kit, day bag, night bag etc. This makes it easy to reach into your locker and take out whatever it is you need, rather than spending ages searching through a jumble of things - the lockers are narrow and deep so things get buried easily, and it's always a scrum on the truck as everyone tries to find their stuff. Make life easy for yourself! Take plenty of camera batteries although the charger on the truck is fast and there are quite a few sockets so no one had big problems getting things charged. Also have lots of memory space - I would recommend at least 4 GB for a 10 MP camera. For the school visit, you can buy things to take in town on the way, so don't worry about bringing things from home. They are also grateful for cash donations. Be prepared to stand up in front of the class and do some very simple teaching (e.g. reading out the numbers from 1-20). It can be surprisingly cold, especially in the back of the truck, so take a good fleece. Also I would recommend at least a three season sleeping bag, if not a four season, as those with lighter bags found themselves cold at night. If you go white water rafting, you will certainly fall in many times so go prepared. Be wary of pushy salespeople when stopping off on the journeys, try to stay in groups and don't be afraid to say no - and always haggle! A pack of cards will make you popular with fellow travellers, and a head torch is essential - take it everywhere towards evening as darkness descends very quickly.