Worms World Party is ultimately more or less a clone of Worms Armageddon. At least the interface is very similar to WA and the game hasn't changed much. There are some new features, e.g. game modes that you can switch on, like only sheep in the boxes, or superrope mode.
Install, service pack on top, crack on top if necessary, finished. OK, maybe you should set up the Explorer Hack if you want the menu to look good. Does not go for the GOG version, as this one works quite well. Ingame is actually doing quite well anyways.
For WWP servers you have to forward ports 80, 6667,17010-17012 (TCP). You can either go via the LAN servers (good on LAN, because you don't have to enter IPs), or connect directly to the Internet, via the IP/domain of the host, or you can go via the Worms servers of Team17. For private games, however, I recommend the direct variant, save the annoying childish things like password for the server, and the like.