Shukran to both of you!
Isa, which dialect do you speak? Would you say all Arabic speakers have a knowledge of formal Arabic in addition to their respective dialect?
All speakers have a passive knowledge of formal Arabic, as they are constantly being exposed to it: whether in mosque or Church, it is the only language of liturgy and prayer. Of course, their grasp of standard Arabic varies widely. I noticed that Morrocans, whose dialect is unintelligible to the rest of us, who speak standard Arabic, speak it at a high standard (if prone to hypercorrection)