Hondata

1) I've already re-purposed the brake switch input for something else, will this be an issue for traction control to function properly?

2) Given it's a front-wheel-drive car is there a need to hook up the rear wheel sensors up to the unit? What purpose do they serve? I think it may be so the system can see that the front wheels are spinning faster than the rear and thus slipping, but wanted to verify.

You can use a different input for the traction control.

You must have both front and rear sensors for it to see a difference between front and rear.

So it does not depend on the Brake switch input being stock/operable to be able to distinguish when brakes are being depressed?

no