Boarding: We waited until around 3:00 PM (3 hours into boarding), and we practically walked right on. Our bags arrived in good time.
Stateroom B414 (mini-suite, mid ship under Sea Walk on port side): The staterooms under the Sea Walk have as much as twice the balcony space as most other staterooms. There is plenty of room for two reclining chairs, two ottomans, and a large table, with no lack of privacy at all from sea walk above, except when standing at railing. In addition to the extra space, you have the advantage of looking down to the sea instead of to lifeboats. I would definitely book a room under the Sea Walk again. You should know, however, that a soft blue light from the Sea Walk does illuminate the balcony at night. It's not bright, but to keep the room absolutely dark for sleeping, one must pull the draperies closed. If you don't mind the soft light, it's sort of like having a night light. We liked the curtain between the 'bedroom' and the living area that allowed one of us to sleep while the other was awake in the living area.
Beds: a little firm, lovely pillows and bedding. No sheet, just a duvet for the top cover. Perhaps one can request a sheet. We just turned down the thermostat at night so we wouldn't be too hot.
Extra large balcony with no loss of privacy from above except when standing at the railing.