i cant answer question 1 but..
2) half of silver spurs answer is correct
1. If prior to takeoff with Brake Fans ON, the brakes temp. exceeds 150 degrees, it is likely that the brakes temp. will exceed 300 degrees during Take Off roll as the Brake Fans is switched off.
but the reason is not because of fuse plug its:
The FCOM limits brake temperature to 300 °C before takeoff is started.This limit ensures that, in the case of hydraulic fluid leakage, any hydraulic fluid, that
may come into contact with the brake units, will not be ignited in the wheelwell.
This limit does not ensure that, in the case of a high energy rejected takeoff, the
maximum brake energy limitation will be respected.
*quoted from the airbus330 FCTM
3)
REC MAX FL reflects the present engine and wing performance and does not take
into account the cost aspect. It provides a 0.3 g buffet margin. If the crew inserts a
FL higher than REC MAX into the MCDU, it will be accepted only if it provides a
buffet margin greater than 0.2 g. Otherwise, it will be rejected and the message ”CRZ
ABOVE MAX FL” will appear on the MCDU scratchpad
*also from the FCTM(busboy's best friend)
time to read your books sir.