You should be able to use your current ISP, but a cable modem or DSL is a good idea. You'll need to get a Bluetooth access point that plugs into your home router or a USB Bluetooth adapter for you PC that will share the Internet connection with the PDA. We have several access points and adpater reviews on this site.
I never knew that a Bluetooth module for the Prism was available. What brand is it? It should have come with instructions on how to connect the PDA to a Bluetooth phone for Internet access.
You shouldn't have to worry about Bluetooth security, but if you are, turn off discoverable mode on the PDA so other devices can't find your PDA.