I have heard from people growing any Cordylines in Melbourne if they have the right conditions. If you are going to build a hothouse I don't think you are going to have any problems as long as you keep it warm and the humidity high. I heard from a lady who had cordylines growing under her patio very sucessfully. She had a tropical type garden all around her that was creating the right enviroment they needed and has been growing her cordylines for a number of years now.

The Cordylines you have mentioned in the list are probably some of the more 'tuff ones' I'm not so sure with Miss Andrea but them you never know till you try. I would steer clear of purples and oranges (except Schubertii) and give anything else a go. If you're having sucess with everything you could possibly try purples and oranges if you wish.

Good luck and we'd love to know how you go. If all else fails.... just move back to QLD!! Lol.