I had been through the canal six times on the USS Boston (three tours of duty in VN) and wanted my wife to see the canal. We watched from the lounge and it proved to be a wonder for all the folks that were in with us.
We ate most of our meals in the buffet and the food was outstanding.
We did not go into Colon because there just wasn't anything that tickled our fancy. The timing was really a question and I called the Norwegian folks to find out about it and truthfully they lady I talked to did not have a clue. T found out about the timing by asking the question on Cruise Critic. The answer is - if you have signed up for an excursion you get off the ship via tender in Gatun Lake and go into Colon, before she turns around.
Cabin was the standard 185 Sq. Ft. with no amenities in the bathroom - - which nowadays is standard. We used to get toothbrush, toothpaste, razor and several other things but no more.