Originally Posted by canadiancow

a) No. The only time you EVER have to pick up luggage in YYZ is if you're transferring to a DOMESTIC flight. And even then, it's only under certain circumstances.
b) It may appear on the boarding pass, but it has no meaning. Everyone who wants to fly to the US has to re-clear security.
c) Follow the path that everyone takes. Before you get to the big escalators down, veer off to the right. It should be very obvious that this is for US connections. It will be the F gates.
d) No
e) If you also have Global Entry, you can use the Global Entry kiosks after clearing security. US transfer security has always been pretty dead when I've been there, so I have no idea if there's a NEXUS line during busier hours.