I will speak to some of this, as we were on the same cruise. The staff was amazing. While we have had a couple of NCL's this year where the service is lacking due to staff:customer ratios, this was not the case on the Star and Antarctica.
In terms of clothing - we brought way more than we needed. We could have easily taken only half. And this is from a FLA gal who does not like it below 70*. The ship itself is well insulated. So the only need for outer clothing layers is for the excursions and walking out on deck. Although the 1st day of Elephant Island, they served hot cocoa and churros up on the pool deck. My husband only wore a single long-sleeved shirt with a winter vest on most of our days outside.
Keep in mind that Buenos Aries will be having summer, so plan for 80* on the beginning and end days. And do take the time to stay a few days before and after if your schedule allows. There is so much we want to go back to Argentina for now. After all you are flying so far and just skipping a lovely portion of the trip.
In terms of 'being worn' we did not find that to be the case. It was refurbished in 2021.
I hope that helps and have a great time!