Is it easily possible in GNOME 3's gnome-shell to achieve similar appearance of windows' title and menu bars as with Unity's Globalmenu?
To answer you directly - no its not "easy" for gnome-shell to have unity's global menu.
However, there is an alpha quality gnome-shell global unity patch available (patch below).
As to redisplaying the minimize-maximize and close decoration back-into gnome-shell - just use gconf-editor and change the key shown - note the position of the close - minimize - maximize buttons
Compile Gnome-Shell global menu
open GNOME Tweak Tool (install it in Ubuntu:
Now open Dash and search for Startup Applications
Add an entry
Complete the installation:
You can also look at this post: http://www.webupd8.org/2011/09/get-global-menu-in-gnome-shell.html. It's about the same extension, but it provides instructions for different distros and Shell versions.
To hide the window title use maximus: http://www.webupd8.org/2011/05/how-to-remove-maximized-windows.html