router/xp configuration for access a public wi fi network

suppose i have a public network foo accessible from home.

1.
how can i connect to that "wan" using my router (asus wl500g) ?
(bridge option on the router requires mac address and i do not
know that).
i just need help with the wan portion since lan portion is obviously
a no brainer (well... would wireless traffic on the lan portion
coexist
peacefully with the wireless wan connection?)

if i can't do that:
2.
can i connect to that network AND to my router i'm running printer/
shared storage of
using the same wifi card in the laptop or do i need one more wifi
card to connect
to both networks simultaneously?

thanks for tolerating my multiposting.