Firewall/NAT

When I was using FreeBSD itself for NAT on my network I used to use the deny_incoming flag for natd (link) to ensure that I wouldn't get any incoming traffic that didn't match up with outgoing traffic.

Is there an equivalent setting for m0n0wall, or is it not required?

I haven't made many configuration changes (other than IP range settings) so is it OK to hook up my WAN port to my cable modem connection with the default configuration?

The only Firewall or NAT rule set up is the default "Default LAN -> any" one.

With thanks.

Andrew