Yes, compatible; the so-called "fix4bike" ball joints have 2 lugs on the underside of the ball joint (for greater stability), but require a specific "fix4bike" mounting.

Yes, it works perfectly. I have a Model Y and an EasyFold XT3 myself. Already used umpteen times. Please note: Connecting the plug - as standard - can be a little fiddly (doesn't seem to be fitted in the same way on all models). The problem is that when "screwing in" the plug from the EasyFold, the cover of the socket from model Y protrudes (or can protrude -> as I said, not fitted in the same way on all models... for whatever reason) on the underside of the cover/bodywork. If this is the case for you: Simply unscrew the can on model Y, turn it to a different position (in my case it was 60° anti-clockwise) and screw it back on. I can now open the lid of the can wide enough and the problem is solved.