You don't want the Bluetooth dongle. That's not WiFi.
A WiFi dongle won't pick up the signal as well as a PCI card with a decent external antenna, but if the signal is strong enough, you can move the dongle on its lead to the spot where you get the best signal.
Your neighbour can read all the stuff passing through his broadband connection into your machine (if he really wants to), but he can't access your machine unless you enable sharing on it.