1. Becoming much more so
2. B747-400, + 2.0 tonnes with packs off, +1.9 tonnes packs APU to pack (lose 0.1 tonne due APU door drag)
3. pass
4. B747-400, yes but have to be prepared to cancel to control any swing then revert to symmetrical reverse thrust (ie if eng#1 failed, only use rev on #2 and #3)