My son attends a primary school for the deaf and hard-of-hearing here in Europe. Most of his fellow students wear hearing aids or have cochlear implants. Lip reading is no longer being taught, it is a dying art in our part of the world. Most of my son's schoolmates can hear only wearing their equipment. Since most of them got their CI as infants, their speech is good. But despite that, theirs is still a world onto itself.
When I first stepped into this environment I felt like a complete outsider, and still do many times. The school is bilingual - instruction takes place in both spoken words and sign language. Many of the deaf teachers go without CI and rely completely on sign language (lip reading fell out of fashion about two decades ago), which makes it very difficult for non-signers to engage in conversations with them.
Some of the students' parents are deaf too, and what I've found is that many of them do come across as pretty defensive, at least initially - like the folks on the forum for the Deaf that was mentioned here. I don't blame them. What I see 'growing up' alongside my son and his school friends is that the deaf have to put up with lots of insensitivities (to put it mildly). It starts when they are kids - lots of teasing and bullying from kids in their neighborhoods who make fun of the gestures the deaf kids rely on for communications. And then there are the legions of hearing folks who think that deaf people must be retarded as well, or simply require hard shouts to follow conversations. I cannot speak of serious discrimination, but there is a great amount of micro-aggressions that deaf folks have to swallow day in and day out.
Anyway, not much advice from me in the above. Just sharing my experience. I will say, that you learn a whole lot about any other culture by simply stepping up to people and make friends with them. If I were you, I'd get off my chair, and start visiting clubs for the deaf, coffee bars for the deaf etc. Do more than paper research. Really get out there. Immerse yourself into their physical world. This may take time, most likely longer than you're used to when building new relationships, but you will learn much more from actual face-to-face contact than any book or online stuff.
Good luck