You can check in as late as the ranger station is still open, after they close, for any expected check-in they will leave a packet with everything you require and you can complete check-in the following day when they reopen.
I believe they left check in packets in a box by the store for people who were checking in late with trailers. I don't know if tgat works for cabins. We checked in during day so I'm not sure.
I'm unsure. We left pretty early to make it on time and we got there an hour early. This gave us enough time to eat somewhere.
Thanks! Your answer is awaiting moderation.