The novels really like to refer to each other when possible, but you shouldn't let that make you feel like you've been "missing" anything. Often, characters in onscreen episodes would have backstory you'd never seen, like Picard meeting old friends, etc. Just pretend it's like that, and move on.
I promise, the A Time To... books are the first books that Really Matter in the 24th century ongoing continuity, aside from the DS9 Relaunch which you also mentioned. Don't worry about it.
I promise, the A Time To... books are the first books that Really Matter in the 24th century ongoing continuity, aside from the DS9 Relaunch which you also mentioned. Don't worry about it.