Knowledge is eventually gained, someone would have built practical devices relating to nuclear fission, whether that was a bomb or a reactor.

Nazi Germany would not have done that in any time frame relevant to WWII. They specifically rejected aspects of atomic/quantum theory because they were tainted by "jewish science" which unknowingly set them back decades and sent them in the wrong direction. As much as they were obsessed with super weapons, they were very unscientific in their R&D.

Maybe maybe not. Camo is just about playing the odds, nothing works from every angle or circumstance. If tires on wings means 5% more planes survive it's probably worth it.