777 main gear and 747 body gear have no ability to do anything but stay inline with the longitudinal axis always.
On the ground the rear wheel pair on the 777-300 will turn but thats all.
Um, no.
The entire body gear on the 747 turn in the opposite direction to the nose gear, when on the ground.
I can't remember the figures off the top of my head but they start at about 10° nosewheel steering and move at about 10% as much as the nosewheel.