Custom USB PC-PC Interface
A "bridged" cable. Unbridged A/A cables should not be made and may harm your computer (2).


3/4. This depends on your cable. The bridged cables usually pretend to be two Ethernet interfaces joined back-to-back. The exact interface will depend on your manufacturer.

(Implied) This will almost certainly not achieve 1ms latency; you are much better off connecting them with a short gigabit Ethernet cable and achieving synchronisation over that.