1) Definitely hire a Realtor to represent you. There was a buyer on Trulia Voices a few weeks back that had a pretty scary story of the builder taking away the property that they had negotiated already.
2) Make sure your Realtor is experienced in negotiating with builders. Everything is negotiable in this market, especially with builders.
Hope that helps,
The location is very nice and the central. You wont go wrong by purchasing a brand new home in Mtn View. The only concern is the lot size for new homes they're very small. You may want to look at newer homes currently in the market with larger lot sizes.
Let me know if I can help in any ways.