The hardest part will probably be the installation, but if you can follow a youtube guide you’ll be fine. Go for a distro like PopOS or Fedora that have polished out of the box experiences.
A fraction, but still not an insignificant amount. Either way, all it does it change /sbin/init to be a symlink to systemd. That’s the same exact thing distros using systemd by default do.
All it does is symlink init to systemd. That is very unlikely to ever cause a problem. It will function the same as using SystemD by default. This distro has been around and working well for quite a long time now.