Gear for the Arena.Follow

I am planning to get the Merciless Gladiator from the pvp rewards,

and then doing 2v2 Arena with a Rogue or Frost mage
and then doing 3v3 Arena with a Rogue or Frost mage and Priest.

Will I be geared enough to survive with the Merciless Gladiator rewards and a few other pvp rewards. and then getting the pvp dagger.

Good gear won't save a bad player. But yes a full set of Merc Gear will help considerably compared to PvE obtained gear. Their resilience and HP stats are key to PvP gear. Also arenas are matched up on a rating system. You will be fighting other people of the similar rating as you.

As for the best Battleground? The one that wins. Each battlegroup is different, for mine I would do AV since we win a lot and it is the fastest honor. Joining competent premade BG raids is hands down the fasstest honor, but those tend to gear check you and require 250-300+ res.