You clear immigration at YUL.
YUL connection guide.
https://www.admtl.com/en/guide/connecting-flights
You will likely pickup bags if it is overnight connection.
YUL arrivals will be empty at 11PM. All the European wide bodies arrive mid afternoon for evening departures back to Europe. Not many flights to/from Asia.
Hotel shuttles are usually at departures level of US departure terminal and you should have a clear view of arrival shuttles while staying indoors.