For a comprehensive answer you would have to consult with an attorney experienced in the laws of your state, and who was aware of all of the facts of the situation.
Yes.
Only if the child has a severe disability.
if court approved.
With an approved motion to modify.
No, but the child is potentially eligible for RSDI payments based on his disabled father's eligibility, and these payments would count toward the father's child support obligation.
This can be the case yes depending on the disability, insurances etc.
He needs to file for a modification. See Dads House link below
The father is responsible for paying at least the state mandated minimum in support regardless of what type of income or assistance the mother has. That is considered her portion of support, child support is yours.
Only if approved by the judge.
If a child is receiving money from the government because one parent has a disability, chances are that the parent will not be expected to pay child support in addition to that money. The court order that is in place controls what happens regarding support.
Not if it's approved by the court. see link
Child support is calculated based on income of the father (or mother in such a case). If the father is unemployed his child support will still be calculated based on whatever minimum wage is in your state. The only time this does not apply is when the father is on disability. Welfare shouldn't matter.