You'd be very welcome. As for the oil, not quite sure what you mean. 50/50 is just what it says. Just fill with half ATF and half gearbox oil. If the oil in the box is in decent condition, then I'd run say a litre and a half out, then top up. It's a cheap and simple way to know if it makes a difference. If the oil is shocking then it wants draining anyway doesn't it!
Axle oil is 80W 90 standard stuff. There' really no need to look for anything special here. I get mine from the local car parts place. As for engine oil, 10w 40 I get mine when it's on offer at Tesco. These are a light truck engine and could probably be run on a mix of gravel and badger wee. There's no need to get F1 racing oil for them. Just use a genuine Toyota oil filter though. It's not that pattern ones don't work or endanger your engine, but the genuine ones absolutely do filter better for longer. Timing belt is a 15 minute job but worth considering a new tensioner whilst you are in there. It's not utterly crucial but if you are getting a garage to do it, rather than do it yourself, I'd be slightly happier knowing it had new parts. If I were doing it, I'd inspect the tensioner and put it back only IF it checked out ok. You can't guarantee the garage will do that.