The passports were probably taken by “Mr. Ali,” the guy who arranged their flights and no doubt provided the stolen passports for them. Personally, I don’t think they were terrorists; just people attempting to sneak into a European country (where at least one of them, the one bound for Frankfurt, already had family).
I have no idea ... having not been on the plane. Is starting to get nasty though between agencies. Not good and less sharing of information is beginning due to mounting pressure but know not where that pressure is coming from or rather which agency or agencies. Will not be good for future security either in that region of this world. (imho) ... France is taking a lead, of sorts though, and filing charges.