Yes it’s fairly simple to do, essentially the user needs to download an image of a Linux install disc, flash it onto a USB stick (or a Dvd I guess), and then reboot their PC. They may need to press a key at boot to open the boot menu and select the USB (or the bios to change the boot order).

After that, most distros offer a very easy to follow installer which will install the new OS.

Most Linux installs can be done alongside windows (on the same hard drive or it’s own drive) but windows tends to break the boot loader with updates. It’s gernallt better to only dual boot if you’re good at fixing things - otherwise a full Linux install is better.

The most inportant thing is back up all your important data, and only do this if you genuinely want to leave windows. I’d make sure your windows license is digital before doing this too as that allows using windows again if you want to go back.

I’d say anyone can use Linux, it’s user friendly and robust. In terms of installing Linux, I’d only do it if you are sure you know what you’re doing - installing any OS - including windows - can involved trouble shooting problems.