Bite wounds

How I can tell which limb its on; if that will let me do anything to heal it.

It’ll let you know when you got bit.

The zombie lunges forward trying to bite you!
The zombie bites your left arm, doing 11 damage!

Also I think if you are infected on the character screen it will let you know which arm once the bite wound starts hurting.
You can also use “P” to check previous logs if you missed the message of the bite.

It appears all I have to do is cauterize, not even knowing which limb it was.

Yeah, that more or less takes care of it. I’m not sure if you can still do that after it becomes infected though.

Antibiotics heal you when the infection turns ugly.

you can also use first aid kits if you need to