I have successfully applied the first one, the second one I haven't because I do not give my users rights to use Terminal. (Though if they were smart enough, they'd download an alternative to Terminal)
once you do this, the User, assuming they aren't Admins, won't have access to the Users preferences. I have done this to multiple PreferencePanes and have seen no problems yet.
2. sudo chmod 750 /usr/bin/passwd
this will do the same to 'passwd' if you've given users access to the Terminal.