Without being there, hard to tell the exact type of spin. From what you describe, it is likely he is also changing up the bottom and topspin component to fool you more. If it is pure sidespin, you only need to make a touch shot with blade exactly opposite tip up or down, doesn't matter much. You are side-swiping the ball and continuing the spin, so the ball does not react much off your rubber if you read the spin correctly and the blade is going with the spin. Once you get this touch, you can learn to drop it short and confuse his timing on hte 3rd ball attack. This is why a "Bananna" flick is suck a safe agressive receive against a short chop serve.
You can also time the "kick" and try to be more agressive impacting ball at hight of bounce with a BH drive right back at his elbow. He is likely ready for that and can counterblock it by you down Fh line. You can also try to take a lot of power off your receive and use a 1/2 lifting/1/2 solid contact to make a spinny, slow ball land deep near endline. If you try the placement around where you describe #4, you might suprise him by simply landing the shot as many opponents do not return the ball there with topspin. Still, since it is a safe, slow shot, he has time to sidestep and attack it down BH line or crosscourt. Hopefully, you landed it deep and sufficiently spinny so that the kick and depth make it discouraging to attack, which gives you a chance to attack if you see it coming.
if it is a pure sidespin, you can also try a very open blade shot where you slice under the very bottom of the ball right off the bounce. The spin is rotating clockwise, like the same way a top (the toy boys plays with) spins. You impact exactly under it right on hte spin axis, the spin will not take effect and make the ball fly off. You have to get right on or very close to the axis of spin with this shot or the ball will kick off your rubber for an error. Taking it off bounce takes away time from opponent and if you have the touch, you can drop it and create your own backspin. This is a tricky shot to do as you have to read the spin exactly, andticipate the sidespin break of hte ball in flight, and get tehree right after bounce. That can be a lot to do. It can also be easy if you have the right preparation and timing. This is why a "Bananna" flick is such a safe agressive receive against a short chop serve. You are impacting the ball on the side axis of the spin where it will not fly off your rubber.
