it’s not secure by design, since it’s not made to be secure, and also uses unstable versions of a lot of packages to make certain exploits work

hp is notorious for pre installing apps that you dont need, it’s called bloatware. you can maybe remove some of those.

installing and using mint is waaayyy easier than reformatting a drive and installing and debloating windows

linux

yes. by staying in europe

yes

android is very sandboxed, so anything you do in termux/userland can’t affect the android on your phone (unless you’re rooted)