Concerning the CRZ thrust rating: There was a bulletin a few years ago which warned about potentially poor A/T performance in mountain wave conditions which recommended setting the thrust limit to CON in cruise to have that little bit of extra power available in case you need it to counter a speed excursion. On the 777 it's a customer option to keep the thrust limit on CLB even drujng cruise, CRZ is still selectable but bizarrely only activates automatically during descent.