This explains everything (I mean absence of the menu and tool sets in your case).
This could be permissions problem, because AutoCAD on first start copies these files to user support folder from inside application folder (/Applications/Autodesk/AutoCAD 2012/AutoCAD.app/Contents/Resources), but in your case AutoCAD can not do this.
You can try to "Reset Application Options" from Application tab of "Application Preferences" dialog (menu AutoCAD -> Preferences, if you don't have such menu - with command PREF)
If this doesn't help - try to solve the problem by repairing permissions on Library folder in your home folder.
You can also try to manually copy CUI files to "~/Library/Application Support/Autodesk/roaming/AutoCAD 2013/R19.0/enu/Support", but I'm not sure if it exists on your Mac - if you have permissions problems, then this folder may not be in place at all.
Maxim