(US West) A friend new to WoW and I will be duoing; Looking for advice.

Hello. My friend, who has never played WoW before, and I will be duo leveling and plan on end game raiding and PvPing as well. I have a few questions and was hoping you all could help me out.We are looking for a fairly balanced US West PvP server with a decent economy. Which servers would you recommend and why? We don't care which faction we play.My friend wants to play a healer (I'm lucky XD). As a duo which class combination would be best? We don't care about ease of leveling, we're more interested in effectiveness at max level. PvE and PvP. Premade PvP would be great, but there's no guarantee we'll find a premade.How important is it for a healer to have engineering for PvP?Edit: I forgot to mention that I don't care which class I play, I enjoy them all.