To use your connection wirelessly you will need to purchase a wireless router and if you connect using an ADSL connection one with a built in ADSL modem. You will not need to have another broadband account as you can share you existing one through the router.
Im not sure about the range it will depend on your surroundings as well.
To use your wireless out and about you need to find a wireless hotspot and most of them you have to pay to use. Once you've paid you'll be given the connection details and then you can connect.