mac dose have problems with port fording but you could disalbe your fire wall the allow it
Yes it does have to be a LAN IP.
For Macs, I have no damn clue.
I've figured it out.(Apple icon thingy)>System Preferences...In the Internet & Network section click the Network icon.Goto probably built in, and click configure.It should show you right there.
It has quite a few things.Let's see..IPv4 Address - Your IP address that you need for port forwarding (I guess the static IP or whatever if your trying to set that up)Subnet mask - Not really sure but when I port forwarded it asked for itRouter address - The IP address of your RouterDNS servers - Has to do with your internet connection through your router I think
DNS Server is your domain name server which is for viewing domain names rather than inputting IPs