>1) if the pro-trans status is expected to change in the (especially near) future. In four years will this still be in place?

The only thing I can see impacting that is a major incident occurring in-state, like how California briefly flipped red after the PG&E scandal. You run that risk anywhere, though.

>2) if Boston is the most LGBT friendly city? is there a better place to move for safety or even just in general? 3) is moving to Boston right now a good idea?

Depends on the areas. You'd have better luck in Easthampton or Northampton, probably. But not Westhampton. Worcester County is not recommended. Worcester hates anything Boston likes, to a borderline irrational degree