It's kind of weird..

My hunter, as a solo toon, was superb at PvP throughout the Burning Crusade expansion.
But my hunter team, didn't do so well.

I've been leveling them, purely for tradeskills, having given up on them as far as being competitive in PvE or PvP.
That's not saying they cannot be good in those areas.
But with my style, other teams offer more for me at least.

Cannot give you information on the pets, sorry.
TKASomething has been the best hunter resource I've found.
Not sure if pet specials would be subject to diminishing returns, but most things that root, stun or fear are.

The glyphed snake trap is fairly resistant to AoE damage, and that's a lot of poisons down at once.
Concussion Shot, on round-robin could keep an opponent at bay.
Scatter Shot is now a base skill, which could be nasty.
Silencing Shot is a marksman skill, not sure if you want that tree for PvP.
I've always liked Bestial Wrath and Intimidation (the latter on round-robin).

Messing around with Trap Launcher..
Have that keybound.
And then mouse broadcast the trap itself > Send Next Click.

I like that you can glyph Mend Pet, which means no more food for happiness.

You could likely set up SetView(x);SetView(x), so each is slightly off.
And then Flare close to 360 degrees around your team.

Entrapment is Survival, not sure if that's worthwhile going for or not.