You may open an LLC. You cannot work for or on behalf of the LLC.

You may be eligible to seek an immigrant through consular processing. More information is needed about your husband’s case.

The missing stamp should not be an issue. Typically, you do not need to provide documents related to your travel.

You need to follow the instructions provided by the Department of State and your home country for applying.

You do not need to invite anyone. They can simply fill out a DS-160 to apply for a visitor’s visa.

You do not need to change the signature before resubmitting.

You are free to complete any immigration forms on your own. You need to make sure you follow the instructions completely.

You need to have your removal proceedings dismissed first.

Either option is viable so long as you follow the law and have all documentation in order. The timing of the transfer is not relevant.

You should contact the local Social Security Administration. However, you will likely need an unexpired card.