1. Apparently yes. That seems to be half the point of this new system.
2. It's not super clear, but during the last live letter when the system was being explained, it was suggested that you could just add armoire stuff straight on to a glamour plate. No need to take it out first.
3. It seems the key is the glamour plates. They manage what pieces are glamoured to what and with which dye. So you could have 10 plates all the same outfit, all different colors if you really wanted to.

Bear in mind this could all be wrong as I'm working with incomplete information.

Cheers.