People have already answered your questions but just wanted to comment we tried Seabourn for the first time after many cruises on Celebrity in Retreat class, and we loved it and will be hard to consider going back to Celebrity.
Yeah, on our last cruise on Ovation, for formal night, we just ate at Earth and Ocean so we could be a little more relaxed with how we dressed, and honestly (and of course tastes vary) we tended to prefer Earth and Ocean to The Restaurant anyway.
I'm on the Feb 25th/2024 Ovation sailing and we had a TK reservation but they ended up cancelling it as apparently the renovation to Solis is beginning during that cruise, so I would guess it's probably March or later before it's bookable on Ovation.
We did ABC cruise this past February. In Bonaire we did an excursion at the Ocean Oasis beach club. It started with maybe an hour on bus, one stop at the slave huts, but most of it was at the beach club which was really nice!