Nitemare

How big is your ship?

I don't see an answer here? I'll tell you on Silversea, in Antarctica, there weren't any formal nights. But if your cruise is a transatlantic with "traditional" ports plus "adventure" ports, you probably will still have formal nights.

Arctic Adventures and Troll are most often recommended on TripAdvisor. Very active Iceland board there.

We made Titanium 2 years ago when they were doubling 'actual nights in bed' plus we get 15 nights for having their credit card. It wasn't much better than Platinum, which gives you free breakfast and late checkout, but it did earn more points, that we like to spend at aspirational properties

yes and yes. All the US flights leave in like a one hour window, so everyone shows up the same time

We did an excursion where you had to get on your butt to slide down a hill of snow. Hard to do that without sitting down.

I'd suggest a drink, instead. The food isn't great and is expensive Gayle's Broadway Rose is a newer version with better rated food and shorter lines

Go here: https://www.re.is/tour/flybus/ Pick the cruise terminal as the pickup area, it will change the drop off to KEF. I am seeing $36.38 as the fare per person. I don't think there are additional fees but I didn't go all the way thru the booking

An alternative would be to get yourself over to the Rowes Wharf Water Taxi station in Boston. Buy a ticket for a later water taxi ride to Logan Airport, the ticket price includes luggage storage. Leave your bags with them and explore Boston to your heart's content. They are right near Faneuil Hall and the Freedom Trail, etc. Or, most hotels will hold your bags for a nice tip. $20 for 4 bags should do it.

@princeton123211 is right, the flat rate taxi works out to about $100 to anywhere in Manhattan with tolls, fees, and tip. Uber can be a little less or could be quite a bit more. Nice thing about cabs is you follow the signs to the curb where they pick you up, while ubers require more walking to find their location There are no "day passes" for the subway. Pay per ride or you can get a weekly pass that works out when you take 13 or so rides in a week

If there are two of you, then their bus makes sense. For more than 2 a taxi would be a better deal. Flybus is also a good option, probably better than the NCL transport as it would take about as long but would be much less expensive

The "take our shuttle" suggestion is BS and is just a cash grab. Like their bus will be faster than a cab or have an alternative route???? Shameful

You might want to ask about toilets on TripAdvisor's Iceland forum. I haven't been in nearly 5 years -- back then, all the gas station toilets were free, as were many others. It was mostly in remote areas that you had to pay. But you will get current and more specific info there from folks who have visited more recently

I agree with @ljandgb. Any of the larger companies, like Troll, will be familiar with disembarking cruise passengers and would likely have a baggage storage solution for you

If there is a basket they would take USD. If it is a slot, then local only