there are some labelled "PVP builds", but in general for PVP I'd stick to the builds that focus mainly on either enhancement or elemental, with some rejuv, instead of the balanced builds that focus on both.
Thats a hard question to answer as there is no real cookie cutter build. There are many different ways with many different focuses and most of them are right. Originally I focused on spells but I came to realize that if you try to play the shaman as you would a mage you're going to be worse than usless. The main suggestion I would give you is first of all recognize that the shaman is a hybrid and that he must be played as such. Then look over the talent tree and read ALL of the descriptions. Think about your own style of play. How you approach a fight. Think about what talent bonuses would compliment your strategy. Also think about how some talent combinations could possibly feed off each other to give you a larger bonus than the sum of their parts. I personally think one of the most enjoyable parts is making the character. Some people prefer to follow tried and true builds that somone else created and thats fine, I don't, but if you do skip over my advice it is worse than seless to you in that respect. Have fun.