If you can show staff your ticket, you're still allowed to enter & stay within the station after midnight. It's pretty safe inside – just don't fall asleep leaving valuables around you to tempt others.
Yes, there is a small waiting area at the station where you can hang out while you wait. Pretty safe and is heated, which is important as the bus station itself is open air and it gets pretty cold in there this time of the year. Restrooms nearby too.
Thanks! Your answer is awaiting moderation.