I'd definitely be interested in the yarrow! It sounds like it grows like Gaillardia. It's technically a perennial but it only lasts a year or two. It will reseed though.
I completely understand about the cat problem! I spray around my plants with Critter Ridder. It smells like pepper and garlic and cats hate it. Just don't get downwind of it while you are spraying-people hate it too!
