why does a shot from a Pak40 bounce off a Sherman's front hull at 20 meters?
It doesn't bounce off, but it doesn't kill either. The Sherman front armour was not coded correctly in 2.4, as it was not compensated for the slope of its armour, as all other tank in FH are. Combined with the decrease in tank projectile damage, this means that the 75mmL48 will not kill a Sherman with one shot in the front armour at any range (though it will kill anything with 10mm armour less).
F-O-U-R 88mm shells from a KwK88mm L56 to the S-I-D-E of a Sherman that stood 60 meters
According to the code, the 88mmL56 is strong enough to kill a Sherman with a single shot to the side at distances under 243 metres. Beyond that, it will take two shots, but it should never take more than two. So the only logical explanation has to be that you either missed, or it at an angle. Three times in a row. As unlikely as that sounds, I checked the code and there's nothing wrong with it.
C) I needed to fire T-W-O rounds of a Panzerschreck rocket to penetrate and kill the at best 45mm thick side armor of the Sherman's rear hull.
This is true, the Panzerschreck is far too weak now for some reason. I doubt this is intended.
Balancing is one thing, but do you really want to frustrate players like this? I like FH2 very much, but tanks have become this strange entity that I cannot seem to figure out any more since 2.45.
As I've said before, there is no random element in the code. The only thing that's a factor in 2.45 which wasn't really a factor in 2.4 is distance.
If they wanted less one shot kills they should have gone with a system that increases your aiming time, so it's harder to hit your targets with precise shots at longer distances...
We wanted to make tanking more dynamic, more tactical and more interesting in the long term. Forcing players to wait for a good aim does exactly the opposite.