If APU gen is operative then all Hydraulic systems can be powered but as the Green system will be being pressurised through the PTU from Yellow (electric) pump there will be limited flow/pressure during heavy use. Blue will be powered by the Blue standby electric pump.
The RAT gives absolute minimum, above a certain speed and with the nose gear up. Turbulence off the nose gear was a problem years ago, I don't know if that has been tackled with increased min speed or modified RAT.
I think. Not having the AMM handy could mean I'm talking utter bowlarks of course.
