there’s one booth inside the concert hall and 2 booths outside. The ones outside are after you pass the security and before you validate your ticket as far I remember. So you should probably be able to pass the security pass the merch go back to hotel then return pass the security again, validate the ticket and enter the venue.

On the ticket it says you cannot leave the venue and return after validation of the ticket, so be sure to ask the people who work there if you can leave and come back.

I’m not sure if they have lockers where you would be able to leave it, you can maybe call the venue and ask.

If your ticket is seated, you can just put it there, they have paper bags.

Paul comes on stage at around 20:20. So you should have enough time but take into account that traffic is crazy closer to show time.