It seems last weeks lower air temperatures may have had an effect on ships adjusting their interior temperatures. This isn't the only report I've heard on a ship being extremely cold last week.
It is very typical you would have an older passenger mix on a 14-day cruise. Also, the schools won't be breaking yet for Spring break.
Your waiter really didn't have that many people (16). That's equal to two tables of eight. Which they handle all the time. But with the Any Time Dining and everyone starting at different times, I can see where their system can get out of sync. It means a lot more trips back and forth to the galley. This is a good example of how those with "Fixed" seating can throw a waiter off schedule when they rudely show up late for their fixed dinner time.
There is a small hand held luggage scale that you can buy now to weigh your luggage. It just hooks on to the handle. If you store the scale in your luggage, just be sure to remember to allow for the extra few ounces that the scale weighs also. You should be able to find them in travel stores, luggage departments, or at airports.
It sounds like you had a pretty good cruise overall.