Flying hours = 900hrs
Duty hours = 2500hrs (MF). 2000hrs (Other fleets)
Duty hours are whilst on company time, whether flying, downroute or in the office.
MF will have the same pay system as LGW, where hourly pay is paid from check-in to clear, regardless if it's a one day 2 sector trip or longer where a nightstop or two is involved.
Edited to clarify: the 900/2000/2500 hrs numbers are the MAX per year, not a minimum.