a)At this point, you need both a backend framework and a frontend JS framework. Backend is typically Rails or Django, with Rails taking 60-80% of the jobs I've seen. Front you can do Angular, Backbone, Ember.. probably others. These are the ones I know.
b)You don't need 1 year of experience in either Rails or Angular to be able to do great work in them and get a good job. With 6 months in each, you should be fine and easily make $100-$150k in the Bay Area.
c)Your perception is correct, Rails will currently get you more jobs than Angular. That's because Rails is more stable and versatile. Personally I think Angular is pretty lame and I hope it doesn't go anywhere, but even somewhat objectively, Angular can't "be the next Rails". Pure JS frontend frameworks just don't have the room to grow that much in the next few years. Maybe much further down the road (5y+), but then it won't be Angular, but FancyNewFramework(tm).