Depends on a lot of factors! One of those factors is protein. My hair builds up protein like nobody's business, so I stay away from it. But in the event that I *have* to use a protein product, I use the BS/ACV as a natural clarifier to get rid of buildup. Usually, once a week is good. You can work up to once every two weeks too, if you'd like =)
No, you don't have to cowash every time. That also depends on a few things. Some people don't get second day hair, i.e., their curls don't last the next day, so they have to redo the process. It's not harmful, so no worries. Other people waterwash, just using the friction of their fingers to get rid of dirt/grease/etc. Just play with it and see how often you need to cowash =) "as often as you washed your hair before CG" sounds like a good place to start though!