For online communication other than Skype, you might want to look at encrypted XMPP (jabber) or www.webrtc.org. Both allowed encrypted voip.

Bitcoin escrow is going to be hard. Gavin had a little escrow service (Clear Coin) at one point, but I believe stopped it to concentrate on core development. His planned solution was to have both parties agree to have the bitcoin donated to a 3rd party charity if one of the escrow parties failed to follow through.

It's a tough problem you're trying to solve. But if you can crack it, the rewards will be probably be good. It seems like a needed service.