Here are links for San Francisco school information you may find useful,
SF Unified School District Map:
Online School Ratings:
Oggi Kashi - 415.690.3792 direct
Broker Associate, Paragon Real Estate Group CA DRE 01844627
All data from sources deemed reliable but subject to errors and omissions, and not warranted.
My son is only 2.5 so I can't really answer your question about the age at which kids learn to read and write here. Regarding curriculum, if you have a preference for the type of philosophy/curriculum you prefer -e.g. Montessori vs. play-based/Reggio Emilia vs. Waldorf - then that will help you narrow down your search here.
If you can't find a preschool you might choose to hire a nanny if you can afford it. Rates are about $16/hr for one child and $22 for two children. Many families share a nanny with another family.