FYI, KDE/Plasma supports all of those features you mentioned:
1. You can set the launcher/taskbar/panel to auto-hide.
2. You can set up the screen corners (or a keyboard shortcut) to show an Exposé-style view of all running applications/windows.
3. You can have a global menu bar.
You can get pretty close to emulating Unity's interface with Plasma, especially if you use Latte-dock. But there are still certain things that can't be done; the biggest to me is having the menu bar (File, Edit, etc.) in the title bar of all the windows (a global menu at the top works though). You can get a button that then gives you those options, which is close but an extra click.
1. You can set the launcher/taskbar/panel to auto-hide. 2. You can set up the screen corners (or a keyboard shortcut) to show an Exposé-style view of all running applications/windows. 3. You can have a global menu bar.