Robert House. No, it makes no sense, but he's Ren茅 Auberjonois playing a character that's pretty much a darker version of Odo.
And he can bring Luther Sloane Victor with him, too.
Given that FNV was pretty much a Star Trek reunion, Bethesda can feel free to bring in more DS9 actors for companions; Avery Brooks or Alexander Siddig would be my top choices...
Yes! 


(I'd love to see him again...an experienced and very intelligent supermutant who doesn't have a personality disorder etc.? - Cool!)
Charon (He seems to like to travel)