Hi
@clintbrown ,
Yes to all of your questions. The are sold as "annuals", simply because they don't overwinter easily many places in the US, though with a little insulation, people in zone 6 and above can sometimes get away with leaving them in the ground. Zone 8 and above its fine to leave them if you prefer (and have well draining soil). They should be dug and divided every 2-3 years even if overwintered in the ground.
Dahlias grow easily from cuttings. In the UK they are generally sold as rooted cuttings, instead of tubers. This year I cut any secondary sprouts that grew, and rooted them up. Every one survived.
There are a few larger dahlias with dark foliage too. (though maybe not that dark)
