Halogoddess! I havent seen you build anything in a long time! You wer a big influence on me to start doing armor. Your work on Kat is looking great, You might try white bathroom caulk to fill in those seams. If you look you can find some that stays flexible when dry and Im pretty sure its paintable as well. I use it to seal in my visors ant works great for that.
You might also try using a piece of foam to test paints on. Id even go so far as to say something other than spray paint if necessary since foam flexes and spray paint will crack/flake if its more than a dusting. Im going to start using foam soon.... maybe I can test paints and let you know about my results.
Regardless, you have a talent for this and Ive seen how resourceful you are, you probly dont even need my advice, lol.
So, in closing, Im thrilled to see you building again, it looks great Ill be back to check your progress and hopefully let you know if I find good paint for foam!