Here is one solid piece of advice I can give you after spending way too much time tweaking Gnome 3 in the last few days: read this Gnome 3 tutorial. Don’t just scroll through it. Read every single word of it. It will save you a lot of time and hair pulling. I promise.
Go to this link for a permanent fix to the missing shutdown button:
http://mustaxe.blogspot.com/20.....tdown.html
Thanks for the info about the gnome-tweak-tool! Gnome 3 is a very different animal and not very convenient!