Only OSL,CPH and STO are proper crewbases.There is also a "secondary" crewbase at MMX,but these are Swedes being scheduled out of CPH.
Basically, cockpit and cabin crews are composed from one crewbase only,as this makes sense economically,but very often there will be a mix for some reason or other.I can fly with a Swede or Dane as copilot a couple of times a month.On intercont. flights with 3,occasionally 4,pilots a mix of nationalities is much more likely.Intercont. cabin crew is always mixed.
The official language of SAS Flight Operations is English.All manuals,checklists,phraseology,etc. is done in English."Small talk" and general conversation is performed in one's own Scandinavian language.Often,difficult words or phrases are translated into something more understandable,the resulting language being,unofficially,called "SASperanto".
"Luck and superstition wins all the time"!