Do you need a bungee to keep the balcony door open?
Where is the plug in the room? Will I need an extension cord to the main area of the room? I always bring a plug you can plug 3 or more into because on CCL the only one is in the main sitting area. Is NCL's in the bathroom?
We were on the Sun to Alaska and didn't use the pools, so I can't help you with that question.
As far as the balcony doors, we did not need a bungee cord -- it's been a little over a year and I forget exactly how they worked, but they stayed open without a problem.
I would definitely take a power strip or extension cord. There is one plug in the main cabin, but I think it was a single outlet. If you've got camera chargers, etc. you will want additional outlet space. There may have been a second single plug in the bathroom, but I don't remember.