You can't access your home broadband away from home, you will need a seperate package.
Wireless Broadband is in its infancy, there are a few sites in public places but I haven't found a site listing them. You would need to be near a 'Hotspot', and signed up for that location.
The most common method at the moment is using mobile phone technology, where you have a mobile inside the laptop to access the internet. This is slightly faster than 56K dial-up, but you incur a mobile call charge.
Accessing your files is another matter. Your PC would need to be on and configured as a server. I know nowt about that!