That should make a really nice conversion
Wouldn't have gone for hub motors personally as there's not a whole lot of weight in a T so unsprung weight will have a big effect, mounting might be tricky with wooden wheels and iirc axle location is by torque tube but hubs are definitely the simplest route all the same. Novel radiator cap
And is that an early Land Rover left hand drive steering box?
I'll take a shot at a few of the questions but I think you'll either find a different diagram or sketch something up for what you actually have, that one seems more confusing than helpful!
1. It's power to an external DC-DC convertor for powering vehicle lights etc and is shown wired into a greyed out main contactor :/ No idea why they would draw in the convertor, grey out the contactor, overlook pre-charge entirely... read up on pre-charge and main contactors, you're going to need both but can put something temporary together just using the battery connector and an isolator switch easily enough.
1b. You mean you have 2 plugs coming from your motors? You're sure your motors are hall sensors? I doubt they've supplied motors that are incompatible with the controllers but it will need checking. 5 of those wires will be for the halls, 3 sensors, 5v and earth. If the power wires are easily identified then the sensors are easy enough to test on the bench, just needs a multimeter, slowly turn the motors and the halls will switch between on and off.
2. I've no idea which port that refers to on the controller, at a guess refer to pins on a socket on the controller rather than on whatever loom came with it.
3. BEMF, back electro magnetic force would be the logical answer but I've no idea why it would be a pin assignment :/ (might just be a lack of knowledge on my part and there's a simple answer).
4. At a guess it's the brake switch. Some use 12v, some use a normally closed earth connection, etc. In this case it's 5v normally open, easy enough to do with a relay if you want to keep 12v on the switch. Could be an e-stop either but that wouldn't usually be done with a normally open connection, you want a broken wire to cause a fault under normal operation rather than finding out about it when you hit the button and nothing happens!
5. Ummm... dash mounted error light? I haven't got a clue tbh but I doubt it will prevent testing.
6. Gear lever/multifunction switch. Connection looks straight forward enough based on the connector block diagram beside it but the pin numbers are the same as other pin numbers on that PDF :/
7. All the grounds on the plug should be common, wouldn't matter which you use. Not sure if the main ground will also be common and I wouldn't take a chance on using it, better to keep all the high current stuff entirely separate from the control circuity (often isolated from vehicle ground too).
8. Usually 5v (but not always), same connections as question 2. You really need a diagram for just that socket on the controller, there should be a 5v supply on there for it but you need to know from which pin.