I've only had experience of a big one but there's quite a lot of info on the net abut smaller ones and pruning -worth a look. Assume you know both leaves and seeds are very poisonous, as I was firmly taught when I was very small.
Don't plant where they can fall into a pond.

They get about 25 feet high - you can prune, I used to do it annually immediately after the flowers were finished, mostly to prevent seed drop, but also to control the size - I just wanted it small where it was. Cut off flowered growths, but the trouible is, its a bit later than it should be done now, unless yours has only just finished flowering, and you may lose flowers next year.