I have an Eva flight (BR 26) arriving into SEA @ 19:30 in October. I will stay at the HILTON SEATTLE AIRPORT & CONFERENCE CENTER after arriving that evening for a night and they fly out on AS's 6:50am flight (AS 238) to SAN the next morning.

This will be my first time ever arriving internationally into SEA. According to the Port of Seattle website:
What do they mean by "bags being transported via subway"? Aren't the carousels located the CBP facility? Are they implying at some point of the arrival flow, pax have to take a train, bags are re-deposited at a point where it will reappear at a 2nd carousel landside????

Anyhow after exiting into landside, can I go upstairs to re-check my bag at the AS counters and get the BP for the SAN the following day? I prefer to just have my carryon with me for the one night at the Hilton. That way the next morning I can just proceed through security and to the gate. The AS website states check-in can be done up to 24 hours prior to departure. A 19:30 arrival and 6:50 departure the following morning is way below the 24 hour maximum. But does not specifically state if the 24 hour only applies for online check-in and/or same day.

I highly doubt BR will allow my bags to be tagged all the way to SAN where I can just drop it off with AS after CBP. Though I'm sure BR and AS have interline agreements. This is because I'm traveling on two tickets, (award J ticket with BR & paid ticket with AS) and the connection isn't a same day one.

Also is 19:30 a busy time at Seatac for international arrival?

Instead of taking the airport shuttle to the Hilton, is it possible for me to just walk from the terminal, cut through the parking structure, cross the street and into the hotel? Is that an easy thing to do? I am especially keen to do that if I can pre-check my bag with AS. Given that it is way past 8pm by the time I am landside, I'm not too sure of the shuttle frequency and don't mind getting some exercise and fresh air after a 11-hour flight.