I’m truly sorry to hear of your kid’s autism diagnosis. There was some previous discussion on Autism and permanent residency. It didn’t reach a conclusion and may not impact your case at all if you and your child are already permanent residents.
There’s also some previous discussion about healthcare in Canada but this too may not be relevant to your case as that talks about general ailments and routine check ups or visits. In your case you’ll likely have to deal with specialists and not GPs.
I looked up my companies Manulife group benefits and didn’t find any mention but I suspect that you could discuss this coverage with potential employers after the interview process and for this to be included in your offer. While I have no personal experience with this I suspect that at-least the bigger companies should be able to accommodate you.
As for medical inadmissibility, I think that’s going to be a non issue as long as all of your are PRs now and meet your residency obligation you are eligible to renew your PR as well as to apply for citizenship. Also as far as I know, medical inadmissibility isn’t as much an issue for direct dependents anyway i.e. spouse and children.
But realistically in your case I think the question is what your backup plan is going to be, i.e. in case of job loss would you rather move back to Canada or India from America and do you believe that your child will get better services/coverage in Canada than they would in India. In most of the template cases I always recommend my friends to move to Canada, get citizenship and then make up their mind on wether to stay or go back to America. However your case is not a template case and is very unique.
My $0.02 on the healthcare systems in general is that if you have good insurance through your employer then the American system is vastly superior than Canada. If you don’t have insurance then Canadian system provides better universal coverage. Put more crudely if you’re well off then the American system has no parallels.
Again I’m sorry that most likely I’ve not provided you with any helpful information here. I wish you the best of luck and trust that any decision that you make will be the right decision for you and your family.