International connection at Seattle-Tacoma airport

I am flying from Vancouver to Seattle, then Seattle to Tokyo-Narita, with Delta connection in single ticket. I would like to confirm if my understandings for this connection are correct or not.

1. Vancouver airport (YVR) has US CBP, which means I finish US immigration and customs process at Vancouver and I don't need to redo them at Seattle.
2. Once I check in my luggage at Vancouver, this luggage goes all the way to Tokyo-Narita and I don't need to pick the luggage up at Seattle.

I am especially interested about luggage connection, since I only have limited time (57min layover) in Seattle.