hi
the wireless pci card will provide the ethernet connection between the pc & the router, you can then use a cat5 ethernet cable to connect the router & modem & ditch the USB.
- I'm not sure how easy it will be to set up, but lots of people with more nous than me frequent these forums, so you should be able to get help, if needed.
- you shouldn't need to worry about cloning MACs using a cable modem, though, just power cycling everything is usually enough to get a connection.