As for Dumbledore’s sexuality, depending on how integral of a character he’ll be, maybe this prequel series will take the plunge and explore that aspect of him more directly (which would also add another major layer of LGBT representation in blockbusters), but for now, J.K. Rowling isn’t willing to spill the beans.
Aside from Albus Dumbledore and Newt Scamander already knowing each other from the latter’s time at Hogwarts, it’s unclear how Dumbledore will fit into Fantastic Beasts 2.
However, it’s since been revealed that Johnny Depp will play Grindelwald in the sequel after cameoing in the first movie.
That means there’s a strong chance that these two will run into each other, providing at least one encounter before their climactic duel in 1945.