The character is under a year old. He is orphaned - or abandoned - at an orphanage, and my MC adopts him when he finds out that the caretakers of the orphanage think the child will be forever alone. So because he has a bleeding heart and adores kids, he adopts the child. But I don't know what to do now. The point of my writing is to be accurate - to not stereotype problems that real people struggle with. I don't know anything about Down Syndrome, and don't know how or where to start researching it. Help? Suggestions for other disabilities would be welcome too.
I would guess that there are plenty of sites and blogs for parents with children that has Down Syndrom. If I were you I'd start by google it to see where that leads you. There are probably organizations as well that you could talk to. Then you start talking about other disabilities and... well... do you just want a disabled kid for the sake of showing your character of as someone with "a bleeding heart". I mean... what role will the kid play in the story? If you want to display the joys and hardships of the character raising a kid with Down Syndrom that makes sense. But the last line sort of makes it sound like "I want a disabled kid, any disability will do" which makes it feel like there isn't much thought about that part. But as far as research go, I think there is a lot of material to start with to get a better understanding.
It might be difficult since it's such a wide range within down syndrome. Find sources that are either well trusted organizations or family and close friends of people with down syndrome. Another tip about writing disability: Most books and shows where the person with a disability is the MC, the writer throws in some special talent to "make up for it". Don't do that, because it makes it seem like they have something to make up for, which is offensive.
I do agree that you should do some research on trusted sources. However, I would also like to add that you should make them a person rather than solely their disability. There are many stories in which the story-arch for disabled characters is just about their disability, like they basically have nothing else to them. Give them a personality, interests, flaws, everything else a person without a disability would have. Also, just for future reference, it is perfectly fine to make a disabled character rude and mean because not every disabled person is nice, just like everyone else. Hope this helped.