How can I help my brother?

My brother was born with a below average brain/skull/head size and we were immediately told by the doctor about his condition. What it means is he is a bit slower than the average kids when it comes to his education but he is otherwise a good and reasonable kid. He is now in high-school and quickly turning into an adult. My parents tried to do what was practical for us in terms of his education but schools within our budget cannot provide us with a plan that caters to his needs. He currently attends special education classes that truly don’t challenge him best and he mostly learns things for everyday life that any adult could teach him ( managing money, using public transportation, counting change etc).

He has an idea about where he stands in society but I feel it may be tough for him to accept or a serious blow to his ego in the coming years when he realizes his life might not be as normal as he would like ( I don’t believe so but I feel like I must prepare for such).

The main concern is what his future can be in terms of a career or a job. My parents have long thought of starting a business ( like a Subway or a Burger place) to help him out but I am not sure how viable that would be with mortgage and all. I just wanted to know from you guys if you knew any learning centers that could help him or any ideas for career paths he could take with which he could help himself. Also, what do you think I can do for him?

All your responses are much appreciated.
Thanks!