Not simply because he becomes disabled. There would need to be some other reason for him to lose his rights.
Only the court has the power to deny visitation rights.
see link
married or single?
See raleted queation
at times yes but usually if the noncustodial parent does want to see the child they will be denied visitation rights and not be allowed to see the child
Unless visitation rights for the non-custodial parent were allowed in the divorce paperwork, the custodial parent is completely within their rights to deny the non-custodial parent visitation....however, the non-custodial parent may sue for visitation rights.
Not as long as it doesn't interfere with the access rights.
How does the two interfere with each other?
With court approval and provided welfare is not involved. see links
In American legalese, a noncustodial parent is the non-resident parent who has not been granted care of the child(ren).
Not without the permission of the courts and the mother, AND provided the mother is not, nor will in the future, collect AFDC.
Too complicated to answer simply. See an attorney that does child custody and family law.