1) NPIV is an ANSI Standard, so yes it is the same idea as 2012 Hyper-V Uses.
2) I'm looking for this info as well, will update if I get it. http://www.linuxtopia.org/online_books/rhel6/rhel_6_virtualization/rhel_6_virtualization_chap-Para-virtualized_Windows_Drivers_Guide-N_Port_ID_Virtualization_NPIV.html seems to indicate it's agnostic to the guest operating system, but I have a couple contacts I'm asking for details from.
3) Brocade and Cisco FC switches both support.