As for the exchange, since it's more interactive I2P with multi-homing would be a solution.
Hi kwukduck,
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.
-Dukejer