Yes,  I'd be willing to offer some advice.  I'm currently running:  FreeBSD, MPD, PF, Squid, and SquidGuard for firewall, NAT, and filtering.  I run Linux on the desktops.  I don't know what it is about PF, I was just more intrigued by it than IPtables/ipfw/netfilter.

It is definitely not for the faint of heart.  I haven't done any wireless on this setup, so YMMV.

-Ben