Countryside North Estates is a very nice subdivision. There's a lot of growth in that area, so you would probably have more neighbors to your west in the next few years, but you'd be on .4 acres or so on a regular lot in Countryside North Estates.
There's a great earthquake map resource at http://gis.abag.ca.gov. You can map and zoom in on faults all over the Bay Area. Most of Santa Rosa shakes pretty strongly in a big quake. I won't say don't worry about it, but high quality modern construction is basically going to do okay in a quake. My biggest concern would be on fill or slopes. That's where geotechnical engineers come in handy.