The stud is simply a stud screwed into the casing. Normally, the bolt that holds the alternator to the brackets would be sufficient to ground but running a jumper wire from that ground stud to a bolt on the engine block wouldn't hurt.

Don't overthink it. It's just an additional point where you can ground from. That's it.

Not a bad idea to use it to make sure your grounds are 110% but not absolutely needed.