Viera Link I believe is just Panasonic's brand of HDMI-CEC, but I don't see ARC among the attributes in your link, altho if 3d capable it may be capable. The remote doesn't use the Viera Link literally for control of other brands' units, but likely your remote can be programmed to handle another unit such as the HTIB (or perhaps vice versa on which remote can do what). A Harmony might be an answer for you if they're available in NZ at a reasonable price. Doesn't the manual for your tv specify what other units its remote can control?
"I realize that somebody playing free music isn't as commercial as a hamburger stand. But is it because you can eat a hamburger and hold it in your hand and you can't do that with music? Is it too free to control?" - Don Van Vliet (aka Captain Beefheart) discussing commercial success in the music biz