Oh, I didn't know the formulas were still secret ! I find this a rather weird idea also, now we have every tool to make new weapons/units but still don't know how the values actually works...
About angles, taking into account firer/target elevation difference without knowing the base armor angle give good or wrong results depending on the basic angle : a shot from a 30° angle (from horizontal) due to elevation on a 0° (ie vertical, Tiger front plate for example) armor actually advantages the target with a final angle of 30°, whereas the same shot on an 40° angled armor (T-34 hull...) advantages the firer lowering the angle to 10°...
Things are even more complicated when firing from below target, because here the angles can go up quite high (to 70°+) but there's also a chance to hit the AFV soft "bellow" (bottom armor)...
Well, that's not a very important factor dur to game scale, but taking it "halfways" into account is not very satisfying.
(yes, I'm a grumbler, I know..
)