Welcome to the forums!
1. No idea, never used Hybryde
2. It is a separate distro so I assume its installer would give you the choice to either a) install side-by-side with Ubuntu, or b) replace Ubuntu (erasing your data) so Hybryde is the only operating system.
3. If you are a beginner I don't know why you would switch from the #1 beginner-friendly distro in the world with an incredibly helpful community at http://ubuntuforums.org
to the #127 most popular distro in the world that frankly I've never heard of before today.
What is the benefit to switching between 12 different desktop environments, why not just pick one that fits your workflow and customize it to your liking.