San Ramon has 2 categories. Homes that fall under the City of San Ramon Plan and guidelines and Homes that are part of the County guidelines. Each have slightly different requirements. There are also BMRs in some of the neighboring Cities as well.
You will also need to enroll in a First Time Home Buyer Certification Course Provided by either the Tri-Valley Housing Opportunity Center in Livermore http://www.tvhoc.org or The Mt Diablo Housing Opportunity Center in Concord http://www.mtdhoc.org Both of these organizations are severely impacted dealing with foreclosure counciling but there are work arounds.
Special financing is also required for the purchase of BMRs. Most lenders are not familiar with processing these loans. There are specialist lenders that work primarily with BMRs and Down Payment Assistance programs. These are the folks you want to seek out.