I bought a Logitech V470 Bluetooth mouse, comes with a protective carrying pouch for around £20. You wouldn't need a dongle with that and you can be assured it works. Used it on my Linux laptop already.
I've got a 3G Huawei E1550 USB modem that will also work with it.
Plenty of things will work directly with the Pandora. Just be careful with USB mice and keyboards as they might be 1.0 or 1.1 and therefore won't work without an intermediary USB hub.
Edit: Changed 3G modem to E1550.