She's barking up the wrong tree. ARMUS killed her daughter (unless she's exacting her revenge on who's available -- Picard).
Vadic is really Dr. Pulaski. After falling down an empty turbolift shaft, years of agonizing surgeries have driven her mad.
If they're going with age of the character same with the actors and actresses. Vadic will be to young to be Tasha mom. Vadic born in 2336 and Tasha 2337. Sisters maybe? I've actually thought she was Tasha when I'd saw her.
TrekCore and TrekMovie are both quoting: "Vadic, the mysterious alien captain of the Shrike, a warship that has set its sights on Jean-Luc Picard and his old crewmates from his days on the Enterprise." Maybe a Paramount Press release.
I doubt Q will reappear, however sad that is. I share your sentiment about temporal mechanics. It was the worst thing about DIS and PIC seems to be going/have gone boldly etc... I'm far more concerned about the fact that Tig Notaro hasn't made an appearance yet.
Yeah I think they made it pretty clear that Q "ascended" to his next level of existence. I doubt we'll ever see him again.
Personally I got a bit of a Son'a vibe from the exterior of the Shrike... Between that, the hatred for both the Federation and Picard et.al, and then Vadic's somewhat scenery chewing nature, I'm going with Ahdar Ru'afo's daughter :P (I am mostly joking... though tbh I doubt what they've actually come up with will be much better lol)
There seems to be a poster for some sort of day in the trailer https://twitter.com/geekfilter/status/1579004834182623233?s=46&t=Ow18L0HfY1tH4I0uvzC1iQ