The most common Smilax species with dense, round heads and long peduncles in your area is S. lasioneura (Blue Ridge Carrionflower). Smilax herbacea is similar, but would have pubescent leaf blades underneath. It is also much less common in Illinois. Here is a link that might be useful: Smilax lasioneura description

Don't know about that one. Tho I do know that Sweet Autumn Clematis, while lovel is HIGHLY invasive! The native trumpet honeysuckle, which has a red bloom, is not invasive. But it can get huge. It's gorgeous and hummingbirds love it. We whack ours back by 2/3 each year and beyond that ignore it. I love it. Ours right now is a good 10 feet tall by 8 feet wide and extremely lush. It is evergreen. There are native clematis that you Might want to check into. The blooms are bell shaped and hang down. Ane there is supposed to be a wisteria that is not invasive. But the native one you see everywhere should be avoided like the plague unless you want to spend every week trimming it back. We let one sprig grow at our old house one spring. By the time we moved several years latere it had spread 200 feet down a fence row and we were seeing sprigs starting 50 feet around a third side of the house not to mention it having covered an old barn. I was SO glad to move away from that problem! Dell

Hardenbergia certainly wont and I don't think the Pandorea will either, though I've not planted that, it might need keeping an eye on. As you're in Melbourne I'd try a few Clematis: Aristata (old man's beard) and C. Glycinoides are Aussie natives. Neither produce flowers as dramatic as the non-native varieties but worth a place in the garden. Clematis do need special treatment however, but are certainly not difficult and there are many sites covering their varieties and cultivation. By the way, I posted a pic. of one a few weeks ago in the 'Gallery' page (next one below this page, I think).

It's just in the genetics. The plant must twine to climb so uneven growth on the vine makes that happen. It's 'programmed' to shorten cells on one side. I came across this many years ago trying to get a sure method of telling the difference between Dioscorea bulbifera and Dioscorea transversa. Bulbifera goes clockwise whilst transversa goes anticlockwise. Through observation around the same time I found that most vines seemed to go clockwise. This was on a local level, in my part of the country. I guessed that would also hold for the rest of the world. The coriolus effect only works on huge bodies of fluid, such as the oceans and the atmosphere. It has no effect on a micro level. The old stories of water draining from baths or sinks going in one direction are a myth. Those amounts of water are far too small to be even slightly affected. And plants are affected even less.