if you want to make sure it is really in there, the Finder application is located in MacintoshHD/Library/CoreServices/Finder.
You could try deleting Finder preferences (this once worked for me with an issue similar to yours). Finder prefs are located in your User directory ~/Library/Preferences/com.apple.finder.plist.
If you have Pacifist app, you could use it to just reinstall Finder from your install disk.
You should be able to use keyboard key combos to shut down or restart.
Shutdown dialog = control+eject
Restart = CMD+control+eject
Power off = Cmd+control+Option+eject