1. They are beautiful on their own or as cut flowers, and definitely worth growing. Maybe try them in the cutting garden, too.
2. They need to be staked.
3. Although they make a great show together (see earlier posting from Scotland), I think I might prefer them mixed in the border.
4. You can't always trust the stated color to be what you get - either that, or the dahlias I got were mislabeled. Here's the pale pink 'Good Earth' in my garden this month - yowza!