The Stinson Beach Preschool will hold its annual dinner, dance and silent auction this Saturday night from 6 to 10 p.m. at the Stinson Beach Community Center. It hopes to raise $20,000 for this year’s budget, particularly important for keeping tuition costs “as low as we can,” said Susan Tacherra, the longtime director. The event will celebrate 40 years of the school’s existence: alumni have been invited and photographs old and new will be on…