1. I can't remember ever being able to select my seat until check-in. During the booking process, the US website says "seat map unavailable". I've never tried calling though...it's not worth the time to me for such a short flight.

3. In both directions, the US gate personnel board First Class, then by rows from the rear forward. If you are sitting toward the front of economy, overhead bin space can be a bit tight (but I've only had to gate-check my bag once).