For a single failure Y ENG PUMP LO
PR: ECAM does not ask for YELLOW ELEC PUMP ON (at least in my FCOM), but a note in FCOM 3 says you can use it. The need for it implies a double failure - eng pump and PTU - I think I would leave it off until the approach to avoid pushing my luck...
For a dual hyd failure involving Y ENG PUMP LO
PR, ECAM does ask for YELLOW ELEC PUMP ON. This would keep the a/c in Normal Law and ease the workload considerably. Whether the pump has the flow rate to cope when Flaps are travelling I don't know (depends partly on which other hyd sys has failed?) - the less flight control demand in that phase the better.
DUAL ENG FAIL with fuel remaining - with the RAT running, if the engines don't relight you won't need all that battery power, so use it to start the APU to try a starter assisted relight.
PJ2: lever in FLAP 3 gives 22
deg slat position compared to 27
deg at FULL so a reasonably low Vapp, typically 160 kt. at MLW - GPWS etc. may not be electrically supplied? I don't know if there is another reason such as controllability - a "normal" landing with no flap would also be CONF 3 as opposed to FULL. At some point as speed is reduced the THS is frozen with no engines running, so elevator authority may be a consideration.
MB2002: The QRH DITCHING procedure with engines running says "SLATS and FLAPS .... MAX AVAIL".