German wings operate under the same LCC model as Easyjet and Ryanair. Freight in not usually carried. If Barcelona may be an easy marque for those without good passports but I think the hand baggage and hold baggage screening is sound.
My view is that this accident has all the hallmarks of an accident not an act of terrorism. Most accidents are a result of a chain of events which have a catastrophic outcome. Time will tell.
The aircraft did not deviate. It flew on it's flight planned course. Not every flight is a straight line between two points.
so why is the planned course from Barcelona to Düsseldorf so far off the shortest direct line? it does seems somewhat obtuse but there must be a good reason.