Child support

The short answer is You can not. His income and the income of the child or children's mother is used in the statute to determine the appropriate amount he will be responsible to pay.

No. You are not responsible for the support of your husbands children from a previous relationship.

No you are not, however, I have seen courts try to use the new spouse's income to determine the income of the payor spouse. I would be sure that your husband has an attorney.

I assume you mean for a child from a prior relationship. With that understanding, generally the answer is no, but if he falls behind, assets of his may be seized, even if they're jointly owned between you & him. Schedule a consult with a NYC Child Support attorney for a full assessment.