Number 4 is already possible with X-T10, but I think only with apperture priority. You have to select "A" for auto on the lens and the shutter dial. On full manual I think it does not work.
Not sure if this is what you are asking for, but if you switch your 18-55 to auto Aperture on the lens selector and then turn your X-T10 to A or M mode, you can change Aperture with your camera's rear wheel.