I do not recommend removing the action. The parts are very easy to break, and difficult to find replacements. I personally would wrap the action with newspaper or other paper and tape it in place with painter's tape.
You only need o lightly scuff sand the paint, not remove it.
Try goof off on the key tops. I do not think alcohol will remove the paint.
Meguier's plastic cleaner works great on key tops,but you need a little elbow grease and it smells bad.
Cleaning reeds is tricky. A light oil will clean them up, but if not completely wiped off, can cause scratchy noises, or drip or splash around.....I do not recommend using anything else on the reeds, and never, ever sand them. ( only the solder for tuning)
BTW, when I painted the last 140, I believe I used about 1 1/2 cans of the paint I mentioned before. One is not enough, two is too much.