Crit = Vers > Mastery = Haste
Crit and Vers are your best stats for a very obvious reason.
Haste is not useless, but generally does not do as much for us as the other stats.
Blood Elf is arguably the best Horde Race for Mistweaver as it gives us Crit (our best stat) and a small mana gain via Arcane Torrent.
Pandaren is also good for the Food Buff (Epicurean) bonus, and is likely the best Alliance Race.
Flask: Flask of the Endless Fathoms
Potion: Potion of Replenishment