AT&T EDGE Card Wireless into Router - Help

I live with the cows. We won't see broadband in these parts for at
least a thousand years. With a 300% overcapacity on the copper wire
solution, I finally bit the bullet and committed to an expen$ive
wireless plan.
At the moment my network is running off of borrowed a laptop. I
confirgured the (PCMCIA) wireless connection for sharing, and am using
the laptop to set IP addresses for an XP box, a Win2K box, and a Win2K
Server. As soon as I find the time, the EDGE card will drop into a
PCPMCIA slot card mounted in an old PPRO system running Win2K. I plan
to make that system the gateway, then fee the ethernet connection into
the Internet connection on my router.
Q1 - How do I make this work through my router (Netgear) so that I
keep all but the PPRO system behind the firewall?
Q2 - Does leaving the PPRO system outside the firewall put the rest of
my network at risk (attack)?
I've been root kitted, hacked, virused more times than I care to
admit, and that was with dial-up. Do not want to make the situation
worse.
Any comments will help.
Thanks!
Dave