here is my rough guess, haven’t been able to run VR preview yet with my Vive CV1. But controller idea is pretty much the same. You are in a Pawn, you need to get the pawn owner(a PlayerController), and then get the player index from there(on server), then set the index.
I will have to setup my UE4 first, and possibly just compile from github source to make it work, cause both UE4 and SteamVR is a moving target, compile and update is probably a safe bet.
It’s hard to even find someone that have a vive to do multiplayer test I guess, so gotta find a buddy soon.(I have a few in local indie dev group that owns pre dev kit, so I can ask them to test with me once I got a build going.)
edit: oh, and I don’t know about the answer to 2nd question. not even a guess. ^^;