What procedures will cockpit crew follow during a sudden depressurization?
In the EMB-145 I flew, the procedure for rapid depressurization was:

                   RAPID CABIN DEPRESSUIZATION

         Aural Warning                    Condition
         ━━━━━━━━━━━━━               ━━━━━━━━━━━━━━━━━━━━
         Voice Message            CABIN ALTITUDE INDICATION
            "CABIN"               HAS EXCEEDED 10,000 FT AND
                                        BECOMES RED
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Crew Oxygen Masks ........................................ DON ┃
┃ Crew Communication ................................. ESTABLISH ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

  Passenger Oxygen ................................. AS REQUIRED
  Maximum Altitude .......................... MEA OR 10,000 FT.,
                                             WHICHEVER IS HIGHER
 ┏━━┓
 ┃IF┃  Emergency Descent Required:
 ┗━━┛  ATC .............................................. NOTIFY
       Emergency Descent Procedure ..................... PERFORM

                              * * *


The priority is getting your O2 mask on and then make sure the other pilot was able to get his on as well and help if needed.  The passenger O2 will automatically deploy if the cabin altitude gets high enough but you can force deployment from the cockpit.  If the depressurization is rapid and/or sudden an emergency descent will be performed to get down into breathable atmosphere ASAP (regulatory requirement time limit).  In the case of emergency descent our procedure did have a PA to make sure everyone was seated and seat belted for the maneuver.  

The cabin crew will have their own procedures and while I'm not familiar with them they are equipped with portable oxygen cylinders and have the ability to move around the cabin and assist passengers with masks.