FreeNet could be utilized for the first (if im not mistaking the first beta of FreeTalk has been released already)
As for the exchange, since it's more interactive I2P with multi-homing would be a solution.
Thanks for the info about FreeNet. It would be nice if we had a Bitcoin client that rolled everything into one nice interface; Send and receive Bitcoins, Communicate over a P2P Chat, Communicate over P2P forums and Some kinds of P2P or I2P currency exchange.
I could see where I2P and multi-homing could work since you may want your exchange more instantaneous. Also I could see where P2P could work if you upped the transaction fee. I could see that with a high enough transaction fee your P2P bid or ask would zip right across the network with the highest of priority. Especially if the transaction fee was distributed across multiple nodes.