You are not taxed on gifts as the recipient even when you are a U.S. Citizen. So no, you will not be taxed. You may have reporting requirements to the U.S. government depending on how much money you move into the country.
Since you filed the returns as Joint returns you are jointly liable with your husband for these taxes. The IRS has a 10 year statute of limitations on the collection of taxes. It is possible from the dates that you stated that some of these taxes are past the collection statute. This should be analyzed. It will depend on when the taxes were filed. When you receive the money into your bank account the IRS can levy on it. The best approach is to now establish a voluntary payment plan or...
Not only is it possible, but it may be required. Obtain a W-9 from the person to get the information necessary to complete the 1099, then complete the 1099 and prepare a 1096 form to go with it. If you do not know how to do this, you should hire a local tax professional to do it for you.
This is a very specific question and not easily addressed on this forum. The other attorneys give very sound advice. My best advice is that you hire a tax attorney or CPA that is well versed in this area to represent you. You are embarking on an area that you should seek professional advice to make sure you do not make mistakes that could cost you penalties and interest and possible criminal charges if handled improperly.
How to run an S-corporation is truly beyond the scope of this forum. You must file state forms annually, prepare regular minutes, and maintain the separation between your personal life and your corporate structure. You would do well to retain an attorney or accountant to assist you with this process.
I am surprised he does not already have your social since you are married. He will have it on any past returns. The married filing separate income tax return requires that you provide your spouses social security number. He will not be able to efile without it.
If you were a signatory at the company you could be a responsible party. Don't take this lightly or take the advise of an IRS Agent. They do not represent you and are not looking out for your best interest. Hire a tax attorney to represent your interests immediately.