The canoing was quite hard at first - 50km in two days. Not that challenging but we had wind against us some of the time and by the end of day 2 were pretty exhausted. The staff put the teenagers in their boats so they could focus on nature watching and we didn't have to worry about them. I was glad to have sticking plasters (blisters on hands) and Deep Heat for muscles with me. Suitable thin gloves, the type used by sports cyclists, may be a good idea.
The exodus writeup says it can get incredibly cold at night - not whilst we were there. A fleece or light jacket is a definite, and clothes that keep you covered in the evening to deter mosquitos, but that's about it.
The village school is very poor. Take stuff with you for them. They need clothes - for children aged around 7-9 particularly and also for Ernest and Petronella, who run it. This is one of the poorest countries in the world at present, so they really do need stuff - tee-shirts, shorts, dresses, skirts (girls don't wear shorts or trousers) flip-flops, pumps and sandals - natural fabrics are best. The school has as stock of books, pens etc - did when we were there anyway - but no-one has any food or decent shoes. And there were very few toys about. Also take lots of packets of sweets - the children will love you for it! If you're taking seeds, brassicas, onions and tomatoes seem to work best. Nothing too thirsty. There is a 20 kilo limit on aircraft baggage but a 10 kilo recommendation for the trip. Take a 10 kilo rucksack for yourself and another 10 kilos of old clothes to give away - use your allowance. You'll be glad you did.
The people may be poor, but they are incredibly friendly, dignified and welcoming. And, outside the capital, it does not occur to them to ask for money - they're more inclined to generosity than greed.
For yourself - take a water bottle and a wind-up torch - your two most valuable possessions. Bring chargers as you can charge stuff at Zambezi Brieezers, though not during the main part of the trip. So if you rely on your phone for telling the time, a watch may be useful. One of our party brought hot chocolate sachets which was a great idea.
Opportunities to spend money are few so you really don't need much. There's an initial stop-off for water and snacks, then the next spending opportunity is for souvenirs on your last day. We asked to visit the Chiawa Cultural Centre for souvenirs so we could buy stuff that would benefit the villagers.
Tipping - its suggested you donate 20,000 kwacha each to the village school but this is really not enough - about £15 - £20 each would be good if you can manage it, preferrably in kwacha or $. Tip the driver form the airport when he drops you off. We assumed we could tip him on the return journey but it was a different driver. Lusaka airport takes £, $ or kwacha or a mixture, and gives change in the same currencies, so you don't need to worry about keeping some cash back for refreshments there.
There were up to 5 staff looking after the 8 of us, including an assistant guide, driver and cook. Don't assume you will lose weight on the trip. The food is simple but beautifully cooked on a tiny charcoal stove - our fussy children managed it just fine and everyone always had seconds. There was also, contrary to Exodus billing, wine with some evening meals for adults.
The Chiawa Community Camp sounds quite grand but is actually just your own party in half a dozen dome tents with real beds (bliss) in the middle of nowhere on the river's edge. It also has warm showers, real toilets (sort of) and comfy canvas chairs. Other camping is in 2m square tents about 1.3 metres high so pretty cramped. You put these up yourself, sleeping in a cotton liner inside sleeping bags - you carry your own liner with you.
You can't really swim in the Zambezi(too many crocs) but we did get to paddle once and there is a small pool at Zambezi Breezers.
You will find that you get very close as a group during the holiday. Weeing behind bushes on islands (and most of them don't have many bushes), warthog spotting and canoing brings lots of togetherness. And apart from the school and village visits, you really don't see anyone except your own small group for a week.
If children (or adults) are worried - no, you don't get eaten by crocodiles or anything else. The canoes are incredibly stable and the care taken of you is excellent. We always felt totally safe under TK's leadership.