Distro choice doesn’t matter. Alternately, just use Debian.
It’s hard to use a different computer and nothing will make that easier. If you’ve ever been plopped down in front of a Mac you probably already know this.
Pay attention during the install process and ask questions when you don’t understand something. Don’t be afraid to bail out if you’re worried about messing something up. Make a backup so you can’t lose anything when you do mess something up.
Dual booting is what you’ll do to start with, but windows updates tend to break the system that allows you to choose Linux or windows at boot time. The first time it happens you’ll have to figure out a way to fix it.