This is not a matter that the Articles of Confederation would even interfere with.
Not at first, but there's no guarantee it would not later, or that a law breaking their backs might not be passed.
Not even the Constitution would have done this until the 14th Amendment.
Not the Constitution as we know it no. That might not stop a more subtle suppression of the French language earlier on.
Quebec would ally with the south to promote antifederalism, Quebec would strongly back the Bill of Rights, and Quebec would strongly support Washington's and Knox's plans for developing the American tribes.
Not unlikely.
There was almost a decade of Louisiana being a territory, and experiencing English settlement before it became a State. Quebec would have entered into the union as a state and not as a territory. They were already accustomed to having English overlordship, having to conduct legal matters in the English language when outside of Quebec would not have been onerous. The Germans got along with the English language fine, and so to would the Canadiens.
That would simply not happen with Quebec. By 1790 it had a population of 160,000 historically, and by 1775 even it was bigger population wise than at least three of the 13 colonies. It would have to be statehood on a similar basis or nothing, and most likely the Continental Congress would try and make it easier to open the territory up for the Anglo settlers by attempting to suppress portions of the French identity.
The Articles of Confederation could not have supported this imagined oppression from the Congress.
Perhaps not against English people. Remember, for all intents and purposes the French are seen as a different type of people, and could be considered tantamount to aliens subject to a foreign power or influence.
The First Amendment only applied to the Congress until the Fourteenth Amendment was passed. In addition, from what I understand, the First Amendment's religious statement was specifically made so that the Federal Government could not interfere with a State's state religion. None of which would have mattered under the Articles of Confederation.
The Constitution already was too invasive for many, and it would not have been ratified if it meddled further in internal state affairs.
As it should be because this is an internal state issue.
Again, this could be an exception for the French, and the French were aware of the possibility historically, which was why they declined to rebel (that and nearly a century of bad blood towards the colonists).
I doubt that as territories became states that they would come in as anything other than English republics. Perhaps if one area was extremely heavily settled by the Canadiens.
Quebec was already that, and it remains so to this day. Historically the English speaking population of the Province of Canada didn't outnumber the French until the 1850s, and never did in what would become Quebec proper. This is why I say they might take "precautions" against French dominance early on.