question about H3 vs jap rubbers

It will last pretty much forever if you don't speed glue. Chinese rubbers are excellent if you have strong strokes. If you depend on your equipment for speed, you will have to speed glue hurricane a ton. I am using Hurricane 3 on my forehand without glue but I hit the ball hard. The stickiness on the topsheet will always be there if you protect your rubber and don't use speed glue. For looping backspin, as with any other shot, chinese rubbers require either a driving or brushing stroke to preform well. If you depend on the sponge for spin, you will hit a ton of shots long. For me, with a chinese rubber, i use the hard sponge to hit and the sticky topsheet to loop. This goes for topspin and backspin. A mix of both creates a powerful loop that is great for finishing shots close to the table. Chinese rubbers have more gears than jap/euro rubbers, so they're a bit hard to get used to, but once you do, they're awesome.

I think the easiest way to think of the angles for topspin and backspin, is topsin 45 degrees, and backspin 60. Depending on how heavy the spin is, all you do is change the angle of the racket face. This way there's only two angles to think about. The difference in stroke comes from how much you brush the ball, and which angle the racket face is on. That goes for both jap/euro rubbers and chinese rubbers. The angle of your arm will only ever change from the 45 degree or 60 degree angle by maybe 5 degrees. A difference of 2-5 degrees usually stays on the table anyway. Attacking a no spin ball is probably around 53 degrees.