If there are any issues of difference between the two sets of prints, always ignore the "Colour corrected" ones. Only trust the "Not colour corrected" ones.
No, this is something of a myth. Regardless of the fact that screens are illuminated and prints are not, it's perfectly possible to get a VERY close match, I promise.
That's right. 50% is very high - most people have their screens under 20%. Some people even have it at 0%! So yes, you're absolutely right, you need to lower your screen's brightness until it matches your prints.
However, there is another aspect to this. Please read: https://www.damiensymonds.net/2012/01/light-around-your-computer.html
Oh, and this one too: https://www.damiensymonds.net/cal_starthere.html