George,
They use the same road wheels and return rollers. The tracks and sprockets are completely different however.
1) 42mm diameter, 24.5mm width.
2) 8mm nominally. HL drive shafts can be a fraction smaller, Taigen ones are a fraction larger for whatever reason. Both use the longer shaft gearboxes, same as the Panther, King Tiger, KV etc.
3) see above.