Clematis

Yes I have a beautiful Clematis in a large pot with a metal frame terrace it does well every year with a feed and a few inches of fresh compost each Spring.

As long as you remember to water every day in hot weather and it would help to shade the roots.i have some Japanese forest grass planted in mine.

Yes, I think so. Our clematis has had its best year ever for some reason. Perhaps it likes wind and rain!

Yes, you can. I would avoid the vigorous Clematis Montana, but anything else would be fine. Plant them in John Innes 3 and replace a few inches of soil each year. Keep them watered and give a feed every couple of weeks in the growing season (I use Tomorite, and they seem to like it). If they are in a sunny aspect you could add ornamental grit, or close planted lavender to shield the roots.

Yes, as said avoid Montana series. Viticella types are good if you like slash and burn, as you simply cut them down to 12" in Jan/Feb. I have several in containers that I move around wherever I need some height.

Thanks for all this advice - anyone know when to plant them? I do not have green fingers!

Almost all are now container grown and can be planted at any time. Plant them an inch or two deeper than the original pot.