You will love the A3. The second bedroom has a double sofa bed. Have them add a foam topper and it is comfortable. My 6'3" adult son spent 10 days on it. There is also a single pullman bed.
Pictures here from the Gem twin of the Pearl
Access to the courtyard in fact all of deck 14 is controlled by your keycard. There is a door on the stairway that requires a card coded for access and a slot in the elevator to get it to go to that deck. From your CV there is open access from 4 doors in the hallway.
The climbing wall is no where near the CV and not an issue.
I will provide more details as requested. I have been lucky enough to stay twice in an A3. The service will spoil you rotten.