Do not plant rush. Besides the fact it will look best only when kept quite moist, it will proliferate far too fast and invade any other garden spaces you have and your neighbors. Rush is a great plant...kept in a pot without a hole in the bottom on a pedestal or in a pond or pot pond where it is easy to keep an eye on.
muhlenbergia capillaris is a plant I would like to add to my garden. It's native, and it can withstand moisture or dry however if you do some reading, you will see it grows well in everything but clay. So I would add a little lime and really ammend the soil well. It does not spread by roots and is fairly easy to maintain.
The salix needs care. It is a large plant that needs to be cut back every year however I think it will grow in one season to be far larger than you might be looking for and I do not know if the bark will color as you might like without as much cool weather. I have no experience with this, so I'm not sure but I am thinking about color twig dogwoods and how they struggle here.

GGG