There is a page somewhere in the FCOM detailing the correct calls the PF should make to initiate the actions...........I can't find it now!!
So, I can't answer your questions but in my A330 QRH
You both don your Mask and someone is supposed to make a PA to the pax.
PF starts the descent
PM does the other stuff.
No mention of establishing comms, but we do.
To me the priorities should be
Priority 1:- Oxy mask
Priority 2:- descend
Priority 3:- everything else.
Last edited by ACMS; 25th Feb 2016 at 05:13.