Although the Critical Reaction talent is amazing, I would still always prioritize straight throughput > random bursts. You'll always have CR up. I would gear toward Power.

Gault holds aggro for me very well. I switch him between AOE and Sniper as needed. I went for Gault the moment I hit Tatooine at 27 and, after that, went back and did the side quests with my new pewpew companion. It would be nice to have a Tank pet by now, though. Gault gets smacked REALLY hard. Keeps me on my toes, though.

This seems to be about PvE, not PvP. Survivability in PvE is a Tanks job, gear-wise.

I'm level 28, full Bodyguard. Here's my build: Click Here 10-26 with Mako was easy. A lot of people don't know how to work the companion bar, so they never set Mako into Blaster Stance (or Med Watch if you're Arsenal/Pyro). Expand the bar and keybind those last two spots. All your companions have stances. I set Mako to "Med Watch" and just DPS'ed. No matter what tree you allocate points to, there's no giant benefit until level 20 when you can pick up a signature ability (Kolto Missile, Tracer Missile, Incendiary). For Elites I set Mako to Blast Stance and order her to attack. I just heal her and myself and, though it takes time, we got it done. Leveling as full Bodyguard spec is MORE than viable. It's actually really fun and there's a huge need for Healers for everything from Heroic quests to Flashpoints. I didn't take Ironsights or Mandalorian Warheads because (at these levels) the bonus' just don't shine through compared to what I'm working towards in Bodyguard. Also, 9% Aim is fantastic on paper, until you factor in that you don't really have a lot of Aim anyway. Once you've got Emergency Scan, Ironsights should be your FIRST place you put further points in to, but before that the abiltiies are just too clutch if you're running flashpoints when they're level-appropriate.