As for augments some of my friends go with power, to make massacre hit harder. I however go mainstat for the boost in crit so i don't have to pick up to much in my gear.
also when buying PVP gear i would suggest wading through the Challenger/Weapon-master sets and picking up each piece that has power and surge already on the enhancements and power on the mods. its really up to you as far as alacrity ( I think its nice to a point) but that depends on your server ping. i tend to have OK ping so i run with a bit of alacrity, around 4-5% and i do fine, got to love the static 3% boost from ataru form.
when i run around with one of my marauder friends on my healer i like watching his target of target and seeing the health bars just get, excuse the pun, massacred. he has mostly power and power surge pieces and most if not all of his augments are power and he does ridiculously well.
hope this info helps out and good luck my fellow marauders!