MBTA subway station historical questions

While doing research on MBTA subway stations, I've come across some question that I cannot answer. Any clues are welcomed!

• Chinatown: When were the Lagrange and Hayward entrances closed? Lagrange has an Essex sign (i.e, after 1967) but not modern signage from what I've seen. Chinatown had a series of modernization and construction projects in the 1970s and 1980s, and I'm not sure when they were closed. (I believe the entrance on Essex Street was closed in 1986 when the elevator was added, but that may also need correction.)
• State: Was there ever an entrance from the Exchange Building before the 2004-2011 renovation? This 1938 hints at one ("tunnel entrance"), but it never appeared on earlier maps, and I can't find any other evidence of its existence.
  
  Additionally, was the City Hall entrance exit-only for a while in the 1980s? That and the Franklin Street entrance to DTX were supposedly made exit-only during the 1981 budget cuts.
• Maverick: When were the exits on Lewis Mall closed? Or were they open right until converted to a full entrance in the recent renovation?

I am going of old memories here - bare with me..

I remember my parents complaining about the DTX as an exit only when we walked by it in the 1980's one winter night. My dad said that he could use it go to work, but not come home using it.

I grew up in East Boston my whole life (1980-present). The Lewis Mall exit was never open in my life until the renovation. My memory has it as an emergency exit for some reason back then. The platforms were shorter due to the 4 vs 6 car operations.