Can we get in without printing the day pass,, only have the confirmation email

Yes. If you're there while the ranger station is open, they can look up your reservation.

Yes

Yes, the park rangers pre-print the reservations and post the tickets on each site. They will verify you when you enter the park (during business hours) or before 10am the next morning (if you arrive late or after-hours).

You can.

Yes, as of 2 weeks ago.