Beginner Gardening: Need help with new bed of Purple Cone Flower, 1 by HD28Cat

HD28Cat wrote:
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HD28Cat I have cut the sod away in an area next to my pool and I want to plant Eastern Purple Coneflower (Echinacea purpurea 'Magnus') and possibly one or to other things in the area. I have attached a photo of the area.

1. I would like to put down some kind of mulch before planting. I really dont want to do any kind of hardwood. I would like to use something that has a real dark dirt like look. Can I just use peat? or is there something similar that is very dark and cost effective? Also I need something that is not going to be blown into the pool by wind. Seems like maybe peat would be blown pretty easy when its dry. And then I know nothing about how it would affect to soil PH and all that stuff. Another thing I dont want is anything that has a smell. I dont want manure next to the pool :-) I dont think my wife would like that much. Any ideas?

2. Do I need to treat the area with Preen or something similar before planting? I dont want to put down any kind of plastic weed barrier or whatever its called as I want wantever I plant here to be free to spread and fill up the area

3. Any recommendations on what would look nice mixed in with the Eastern Purple Coneflower?

4. Its hard to tell from the photo but the grass area behind the bed is a pretty steep slope droping away from the pool. At the bottom of the slope I have put in Carlcephalum Viburnum and Oakleaf Hydrangeas. I need to decide on what to plant in between the coneflower and these shrubs. I was thinking maybe False Indigo. But it will be down the slope a bit so im not sure it would get tall enough to rise above the coneflower? Any ideas here?