It's really interesting (and if at any point you take the train west from Centraal towards Haarlem and Den Haag, you can see Het Schip clearly from the railway—it's right next to it—which apparently was intentional so visitors would see this new social experiment). But: the tours in English are only at certain times (otherwise in Dutch), so maybe check.
Interrail barcodes work the ticket barriers at NS stations fine, from my experience.
I'd really recommend renting a bike to explore Utrecht—it's been a revelation living here and cycling. There are lots of bike rental places in Utrecht aimed more at tourists, other than the OV-fiets that need an NS flex pass. In fact I think near Bunk on Vredenberg there are at least a couple, and there is one under the Hoog Catharijne mall that is kind of opposite Bunk. If you're interested in infrastructure, the bike parking under Utrecht Centraal is one of the largest in the world and is fascinating just to look at, although the new one under Amsterdam Centraal is more interesting architecturally. Worth also noting that the canal outside Bunk was a dual-carriageway road until only a few years ago, so a really good example of the changing planning priorities.
On the double-decker trains, the top deck is my preference for interesting views. I would recommend getting the NS app, particularly for information about delays and engineering work. The 9292 app is also useful for journey planning.
In Rotterdam, if you go the the Markthal, leave 20 minutes or so to explore the small museum in the Piet Blom cube houses
https://kubuswoning.nl/ which are just across the plaza (you won't be able to miss them).
It sounds like a very exciting trip!