Louis' illness and themes of the movie

I didn't realize until after seeing the film that it is an adaptation of a French play which was written in the late 1980s and published in 1990. However, based on the use of contemporary pop music, we can assume that Dolan's adaptation is supposed to be set in the present day and not the 80s. Knowing the setting of the source material leads me to a few observations:

1) Are we to assume that Louis is dying of HIV/AIDS? The thought did not cross my mind when I was watching the actual film (I just assumed he was dying of cancer; it is rare for a young gay man in a developed country to die of complications from HIV/AIDS in 2016), nor do I think it was implied, but one would probably jump to that conclusion if you were reading a play about a terminally ill gay man set in the 1980s. (The playwright, Jean-Luc Lagarce, himself passed away of complications from HIV/AIDS a few years after the play was published.) In this context, Antoine's throw-away remark about Louis' high school boyfriend dying of cancer could be interpreted to mean that he has died of HIV/AIDS, and his family is either covering it up out of stigma or did not know themselves.

2) I have to admit that, leaving the theatre, I was a bit stumped as to what theme Dolan was trying to go for in the movie. Having thought about it for a few hours, my best guess is: he was trying to critique mainstream notions of masculinity by showing that Louis, a gay man, made for a better father/older brother figure than Antoine, who as the eldest and a "macho man" with a wife and children of his own, should stereotypically be taking on that role. Martine basically says this to Louis during the scene in the shed, but I think two other moments imply it. The first is, at the very beginning, when Catherine awkwardly makes that comment on how gays aren't interested in having families of their own (this reminds us of that stereotypical notion so it can be proven wrong later), and the second is when Martine remarks on how Louis has his father's eyes. I think I missed this theme watching it because, in 2016, it's not exactly revolutionary to build a movie around the premise that a gay man can be a better family man than a straight man (and I say that as a gay person who knows that homophobia still exists in society), but it would be a lot more ground-breaking to build a story around that point in the 1980s.