Likewise, I'm by no means an OBi wizard. Having joined the party well after May 15th, I decided to skip Google Voice though I understand it is still working.
I am using RingTo with multiple numbers. In my case a single Anveo E911 subscription was required. If you park your numbers on RingTo, each should ring through to your OBi. That said, I forward incoming calls to Callcentric to take advantage of CNAM as you referenced. Your outgoing RingTo CID when calling from your OBi will be the default outbound number as configured on the RingTo website.