I've had castor bean plants from time to time and have not found them to be invasive, even under good conditions. (LOL! Considering how "good" hot, sandy, nutrient-poor beach soil might be.) Also, no problems with my many cats.

You can wait till pretty late in the fall to snip off your seed pods. I think I cut mine back in October and threw them in a paper bag. I had one volunteer come back in the same spot. I keep a huge plastic flower pot saucer in that area that we try to keep full of water. Can't even see it for the plants without really knowing where it is, but the wild critters show up and I guess appreciate the drink. I've never seen a problem with my critters (dog and cat), and we have a big old turtle that hangs out in that bed.