Without you he would most likely be on the street or in prison or dead.
I hope he is able to stay in his community. As opposed to an institution, has he ever expressed interest in something like a group home? I won't be surprised if the answer is no. Many schizophrenics really are not comfortable in any situation except if they can be entirely alone.
Your family is not at all unique, but as I am sure you know, psychiatric problems are the stepchildren and don't get a lot of recognition or community support.
Most states/counties have NAMI branches (National Alliance for the Mentally Ill). This organizations provides a tremendous amount of support, education and assistance and they aim much of what they do towards family members. If you haven't checked them out, I would suggest you take a look. Just being able to talk to others in a similar situation can be a tremendous relief.
I am so glad that you have found a doctor to work with. It sounds like you are doing great, and I know very well how hard this can be.
The discussion you are asking for is a really difficult one. There are things in place that attempt to protect both patients and communities from harm that may come from being psychiatrically ill. But it's very complicated and each case is entirely different. It sounds like you should have no restrictions on driving or pretty much anything else, but Jeff and Jon may create danger both to themselves and others.
So, check and see if there is any support available in your community. I would start with NAMI, but there may also be a local mental health center or the VA may have something.
It sounds like you and your brother could really benefit from some support.