memory management

Using a MacBook Air M1 8GB RAM, is it recommended to allocate 6GB for the guest? Or is it better to divide half for each one (guest and host)?

I allocated 8Gb for a Windows 10 Pro guest OS on Mac. Why do I see that it takes 13 Gb from Mac OS in Activity Monitor? I understand there should be an overhead, but why does it take from Mac OS almost twice the memory allocated for Windows?

I am confused on how memory allocation works. I am using a 2018 15" Macbook Pro with 16GB of system RAM and 4GB of vRAM. I understand from KB124575 that the APIs used by MacOS do not allow applications to directly request vRAM. I frequently run parallels alongside MATLAB, so memory management...