Re: What happened to Vash?
I don't think she's appeared in any of the novelverse stuff, but we did meet the MU version of her in the TNG MU novella, The Worst of Both Worlds. The other day the official Star Trek website posted a preview of Hive, the comic co-written by Brannon Braga, and it showed a Post-Nemesis Picard getting together with her.
They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance. - Terry Pratchett, Equal Rites