Hunter range weapon choice

Yes, but remember that if you annoy the tank you will end up dead and most guilds (or even some pugs) will not let a tank gun go to a hunter for PvP.

Weapon speed used to be the most important factor. Now it is mostly normalised so slower weapons only do slightly more damage for MM hunters. Now you just want base weapon dps. Very roughly 1 Agi = 2 AP (+ a bit of crit) and 14AP = 1 dps so the damage of a higher level weapon will almost always be more than that of a lower level.

Since you are doing PvP, damage dealt is not most important stat. A lower level item with lots of stam and res would be more useful than a lower one. I would value a Bloodthirsty Gladiator's Rifle above something like a Crossfire Carbine for PvP. The Carbine would do more damage, but the rifle has the edge in survivability.

Since there are no PvP weapons yet, grab the highest level you can or just wait a couple of weeks and get a PvP weapon instead.