I don't have much recent experience with NW; forgive me for asking basic questions, since I don't immediately resolve them through a search or FAQ.

I'll be going MCI-DTW-YUL. On the MCI-DTW segment I have seat 21A on an A319, which SeatGuru marks in yellow because of limited overhead storage. I presume it's still better than a middle seat, the only alternative showing. At OLCI at T-24, can I have some hope of better seats showing without a fee? If not, could some open on the airport kiosk shortly before departure? If I wait to get to the airport to get the BP, would I expect much of a wait to get to the kiosk?

For the trip to Canada, do I need to be ready to enter my passport information at the time of OLCI?

Is it one boarding call for all non-elites, so if I am still in that seat I'd be advised to be a gate louse to find overhead storage?