Bigpond don't block p2p. However of course like all Australian ISP's there's no unlimited download options, so if toward the end of the month you find your speed is slow as heck, you know you have gone over the limit & need to wait until the start of next month & refresh period when it's set back to zero.

Try shutting down your OSX firewall whilst LW is closed & then see if that helps. I just bought I new router & found the OSX firewall was clashing with the router's firmware. Different brand router to yours though. OH ... perhaps a reboot after closing down firewall may help though probably not necessary. ie: System Preferences -> Sharing -> Firewall (tab).

I don't have Port forward instructions for your OSX for your device. But it should be similar to those here Port Forwarding for the Motorola SBG 900

For setting up a static ip in OSX, see World of Warcraft Community Site -> Support -> OSX Static ip

Remember after doing this to save your settings in your router (some brands or models also require rebooting router to get the change into action.) And even rebooting your mac might be a good idea too. Remember setting up static ip is the first thing you must do BEFORE port forwarding otherwise it won't work. So if have Port Forward rules set up whilst using a dynamic ip, cancel them & re-do them AFTER having set up static ip. Perhaps it will be safer for you to re-do this if you were unsure about your first attempt. Note: the static ip quoted in the windows instructions may be different to the mac one.