They will not give you a timeline on PvP because they do not know when it will be available. It is like everything else they do in making this game better. If they gave you a definite timeline then for whatever the reason they had to postpone it. Players would say Blizz has broken their promise and they do not want to give us PvP at all. Or your tinfoil hatters will come out and say that PvP will be in an expansion.
There will be specific PvP Gear
PvP will require a special character and or re-roll
PvP will not allow pre-arranged teams
PvP Will be arena only, no way to duel friends
I hope there will not be PvP only gear. That would really mean that the gear you already have will be crap when PvP'ing.
Rerolling just to play PvP are you nuts trying to sell the idea of rerolling just to PvP would be insane
PvP matchmaking will use a system that is similar to the one that they use for SC2. Which is similar to the Elo system in chess. This way in time when your best PvP'ers are at the top. The chances of winning a PvP match will be around 50/50.
There will be no dueling at all, that is what caused problems in D2:LOD the ganking caused more problems than you can imagine. So no dueling at all, all PvP will be arena based. If you can find the link that would show the Blizzcon that talked about PvP then you would have an idea of what PvP would be like in this game.
FYI the PvP patch is 1.1.0 according to what Blizz says.