In the London and Stockholm versions, yes. In Broadway, it was 1988. Other variations placed it as late as 1990.
This is never mentioned, but Florence was raised in England in London and Sydney, and in the US in most American variations. The assumption, I think, is that she was raised in the US in the Stockholm productions. It's not mentioned explicitly.
Again, this is never mentioned. Garry Kasparov won the championship from Anatoly Karpov in July 1985, which is a problem for the London / Sydney scheme, which have Freddie being champion around March 1986; that would mean Trumper vs. Sergievsky is the third world championship in about nine months. That's quite a lot. It would be reasonable to have the previous championship happen in place of Kasparov's 1985 win.
For later dates, it would simply be a question of the current champion (it changes depending on the version) to have beaten Kasparov after 1985.
In the musical corpus, the only real detail provided is that Florence was an English major according to "How Many Women?" ("All of my struggles for qualifications / My nights with Goethe and Proust / Breathlessly abandoned for you / Who thinks Chekhov is King to G3 / And Joyce my college roommate...").
On Broadway, there's a bit of discussion about her:
Later in the show, Molokov details her history a bit:
Most other versions don't even have this level of detail; it looks like you're using the London variation as a basis, but still, it's food for thought.