Yes and no for me
Distro doesn't matter because they only differ in package manager and initial configuration, you can always compile things if you really need it.
GUI doesn't matter because you'll end up with all KDE and gnome dependencies installed anyway because your applications need it.
Experience probably matters, but if it doesn't, it may be because there is just so much there to know.
I would say Linux was more ready for mainstream use 10 years ago. Now with Wayland and (god forbid) Nvidia is quite unstable. And if the best advice is "do not buy Nvidia", then indeed it isn't ready for the mainstream use.
Some of them are your coworkers though.
I can't tell if it's a good news or bad news.
I'm pretty sure it is controlled by a check-mark in panel settings.
They all means the same - free to travel
Up to 5 millimeters