To answer part of your question, the high-income/education zip codes are residential neighborhoods in the hills and more northern neighborhoods. This has been the case for a century. The zips on the lower end are also residential neighborhoods, but in the flats of the East and West parts of town. This area has been in stagnation since the early post-war years. Neither interact with each other almost at all, rarely even sharing schools.

Neither are areas where any business would establish itself, because most all of Oakland are old fashioned post-war neighborhoods. Downtown Oakland, and the meat of the city's desk & cubicle type of office spaces are in the center near the lake and the bridge. This is a very small area without a whole lot of commercial development starts, current or planned. A surprising amount of high density residential real estate priced for upper-middle class types are slowly appearing. These projects are eating away at the old retail/warehouse space that would typically be turned into new commercial development. There is an alternate universe where Twitter moved to Oakland/Emeryville and brought the mid-Market/Castro-East craziness with it...

[Also, there is plenty of violent crime throughout the Valley. It doesn't show up very well in crime statistics and reports because how closely intertwined it is with the poor, semi-homeless and meth. Nobody likes to talk about it, and it is very good at hiding in the bushes (literally).]