Critical Strike: Increased chance that attacks and heals crit. Good stat for Brewmasters because of Celestial Fortune.
Haste: Increases attack speed, energy regeneration and reduces cooldown on Keg Smash. This is not a good stat compared to the others for Brewmasters.
Versatility: Increases damage and healing done whilst decreasing damage taken. Always a good stat for tanks.
Mastery (Mastery: Elusive Brawler): Increases your attack power and gives you massive amounts of dodge. This is your best defensive stat.
You can choose your preferred race as it will not drastically change anything for you.
For weapon enchants use Enchant Weapon - Force Multiplier.
For ring enchants you should do the same as with gems and look at your current stats and think about what stats you feel you need most.
Use Critical Strike, Mastery or Versatility gems depending on your current stats.
Do not forget to use Abyssal Healing Potion!