Ninj, welcome. You'll certainly be able to enjoy great music on your M22s, as I have for a little over six years now with mine.
Yes, the openings in the ends of the speaker terminals are where banana plugs would go. Mine didn't have caps on them, and I doubt that dust would be a significant problem. I understand that some(all?)European countries don't permit terminals which would possibly allow their power plugs to be inserted by mistake, but I don't know if this has anything to do with it. In any case it isn't a matter of any significance here.
No, none of the wires to the tweeter are visible through either of my ports, but this shouldn't be significant either, unless the wire was audibly vibrating against something when it's in that position.
