As someone mentioned earlier, acetone will remove cured CA.
Just put a little on a tissue and let it sit on the spot a few seconds and rub it off. It won't hurt Monocote or Ultracote, not sure about some ARF's with the wallpaper coverings. I use small disposable syringes for applying thin CA to hinges or screw holes, the amount of glue is very easy to control so none of it goes where it's not wanted. If your quick enough with it you can empty the remaining CA from the syringe and clean it with acetone so you can use it again. The only problem is you'll need to know some one who's a diabetic or works in health care to get your hands on some. As far as the Spacewalker hinge gaps, you can seal them if you prefer but I wouldn't worry about it if the gaps are reasonably tight. If the gaps are 3/16" it might not be a bad idea. I have one myself (normal gaps) and I didn't seal the them, flies just fine. This plane doesn't burn holes in the sky so the gaps are no big deal.