Regarding Pan declarations, In Australia at least it is considered an urgency message while a Mayday declaration is considered a distress message. ATS/ATC may treat both as if full emergency procedures are required.
I live near a military base where Pan declarations are made almost every day of operations and the military ATS/ATC do not call upon the aerodrome emergency support personnel. But I have heard civil Pan declarations that were treated the same as a Mayday declaration.
In both situations the controllers do try to extract as much information for the source as possible without adding to the pilots' workload.