Hi Jenny!!! You can't figure out Scott's version of Greek?
I think he is referring to volunteers, but you never know!
When you remove the plants from your beds, make sure you put them in a shady spot, and do cover them with a tarp, but not clear plastic or they will burn. You should also give them a good drink of water while they are sitting out to prevent shock as much as you can.
Then you can add all your wonderful soil amendments to improve your soil like compost, manure, chopped leaves, etc.
Then replant them in the bed in the positioning that you want them. Remember to water the hole well before you put the plant into it, then gently push the soil in around the roots to remove any air pockets. Then water it again. A nice drink of compost tea certainly wouldn't hurt.
A couple of the plants that you listed wouldn't need to be removed if you like where they are placed. They will just grow through the added soil. These would be the variegated dogwood, and your spirea.
I would do this quite soon, so that the plants get a chance to re-establish before the cold hits.
Hope all this helps, and feel free to check in with any questions!