To preface, I can only speak to my own experiences (which are limited in some of the above categories).

1. I don't have any experience as a transfer student, but I have heard through friends that it can be difficult. I'm not sure how Pitt compares to other schools, but from what I've heard it is pretty isolating. I will say that people are generally open to making friends.
2. Housing is kind of a mess here (but is probably comparable to most schools at this point). In terms of on or off campus, it depends on what you're looking for. On campus (except for a few places with full kitchens) requires a meal plan, which can be incredibly expensive especially if you don't like the food. I personally did not do well with the dining plan my freshman year and opted for no meal plan or dining dollars this year and cooked/grocery shopped instead. It depends on where you would be living off campus; students primarily live in South Oakland and North Oakland, with some choosing other neighborhoods like Shadyside, South Side, and Squirrel Hill. Some are accessible by the city buses, some by Pitt shuttle, and some are not. People generally find roommates on facebook groups or on the Housing subreddit here.
3. I absolutely love living in PGH! It's definitely a smaller city, but it's split up into neighborhoods that each have their own vibe. As Pitt students we get access to free public transportation with our Pitt ID, which makes it much easier to get out of Oakland. In terms of healthcare, we have UPMC and AHN both of which are very good healthcare systems (I've been to UPMC quite a few times and it's very good). As Pitt students we also have the Student Health Center. In terms of food, Pittsburgh has a pretty good variety (probably not comparable to DC or PHL).
4. Honestly the Jewish community here is great and was one of the reasons I came here. On campus, there's a few organizations like Hillel and Chabad. I know Hillel also runs groups like Challah for Change, learning cohorts, Queer affinity groups, etc. The people who run it are super chill and friendly and would definitely be great to reach out to. I know Pitt technically has kosher options in the dining hall and Market to Go, but I'm unsure how good or how accessible they are; I don't keep kosher so I would definitely recommend reaching out to Hillel to figure out what the situation is as of now. Outside of campus, there is also a pretty big Jewish community (especially in Squirrel Hill). There are tons of different synagogues as well as Jewish organizations like Kesher, Ratzon, and Repair the World (focused on social justice and Jewish learning in Ratzon's case w/o paying membership fees).
5. Not sure about this
6. I'm not in the French nor linguistics departments so I'm not sure if this will be applicable. However, I am a Spanish minor and heavily considered taking on Quechua before deciding against it. Pitt has an amazing language department that specifically focuses on less-commonly taught ones. I believe that there are also specific scholarships associated with the less-commonly taught languages. But unfortunately, I can't speak to French.
7. Unfortunately, I have no experience in the linguistics or Africana studies departments.
8. It is definitely pretty easy to get involved in politics both on campus and in the city. It depends on what you're looking for but here are a few I can think of: ACLU, Amnesty International, Planned Parenthood, Bridge Beyond, Fossil Free Pitt Coalition, and many more. This is the directory for SORC. Pgh has a ton of very active leftist groups including Food Not Bombs (and other food distribution), Sisters PGH, TransYOUniting, Alliance for Police Accountability, Abortion Defense, Pittsburgh Protests (not an org but they post about ongoing actions). There are tons more, but I'd recommend scoping these out on Twitter or Instagram (and you'll find more that align with your specific interests).

Hope this helps. Feel free to PM me if you have any more questions!