Does the airport have a lounge, my flight gets there 21:00 and next flight is 5am booking into a hotel seems pointless

Yes

Yes nice selection although prices are a bit high compared to other airports

Plenty of lounges you might want to just check around because if you got a nice layover then you definitely have a place to go kick it and have yourself a drink I don't think they really give doubles or anything but I'm not sure what the cap is but you can definitely have a nice drink in this airport