If I understand it correctly, the wallet provides the remote node with view keys so it can find the corresponding outputs, and later the wallet may also send a signed transaction for the remote node to broadcast.
Can someone listening to the communication gain access to the view keys and the transaction information, or is that communication encrypted?
No, the wallet does not provide the remote node with the view keys. I think you are confusing this with the web wallet MyMonero which requires the view key.
The only thing that the remote node will know about you is your IP Address.
Edit: The remote node will also know what are your mixins, so best to keep changing remote nodes.
Edit: To answer your additional questions.
The connection between remote node and client (GUI or CLI) does NOT add encryption from what I read. However, the actual transactions which you broadcast your transfers are signed already by your keys - so already encrypted.
Furthermore, when connected to a remote node you have to read all transactions because on your client side you have to check if the transaction is yours. This will take some time that uses network and cpu resources.
Lastly, the remote node is useful since it alleviates the bandwidth usage and time to synchronize with other peers in the network.
Here is some additional information that talks about what information are sent and received from the daemon (this is also applicable to a remote node)
How much information is passed from the daemon to simplewallet when scanning for a wallet's transactions? Is it safe to share a daemon with a roommate?
