Also I find calling in and talking with one of the "planners" in Santa Clara Counties planning Dept always VERY helpful. Have the lot APN ready when you call. You can do that on your own, or I am happy to arrange for a 3-way call, the Planner, you & I.
Or rather than call you/we can go visit them. Here is their contact info
Santa Clara County Planning Office
70 West Hedding Street
East Wing, 7th Floor
San Jose, CA 95110
Hope that helps!
You would also want to look into what utilities you would need to pull to the property.
Start asking listing agent. Your own agent should be a resource, and if you are going to build get your contractor involve early on as well.