Yeah, I'd be a little annoyed if they left my pond that cloudy. Rock dust will settle, but not so sure how long it would take to clear the cement dust.
Plants will be a unique challenge in a pond with no shelves... at least I assume there are no shelves. However I see some spots where you would be able to tuck plants between rocks - they may need to be placed horizontally, but they will naturally grow upright.
Bog bean would work - it just needs an anchoring spot and then will grow across the pond.
You could also do some miniature cattails or some type of reed, but I think you want to figure out where your best viewing spot is and keep the plants along that edge low. Use the taller plants across from your viewing area.
I'd plant something in the waterfall rocks too, to soften that area up a bit. Some watercress would work - it's a great filter - or some impatiens (an annual but they are inexpensive to plant fresh every year).
A beautiful lily in the center would be lovely - they don't do much for filtering but it would provide shade and shelter for your fish.
And I wouldn't give up on the idea of planting your filter box - I've seen folks drop in a potted canna or a papyrus. Something that's already got a good start. Maybe they wouldn't bother a full sized plant.
Raccoons are the worst - we call them trash pandas. They are so destructive and persistent. We had one that took up residence in our trash can. Scared the you-know-what out of me one night when I went to toss a bag of trash in the can! We started spraying the can with anything we could think of that would be irritating or annoying - hot pepper sauce, peppermint oil, garlic oil, onion juice - after a few days of that, the darn thing finally got the message!