You are free to apply for child's visa even if the issue of child custody has not been decided. This being said, the consent of father will be required for this purpose unless he gives a NOC.

Since the child is in your possession and custody you do not have to apply for the it. If at all your husband wants to have custody of child, he can apply for the same before the court competent.

If you already have passport for the child, there is no necessity to have fathers consent to take the child to foreign country or for applying for visa.

If you are planning to apply for passport afresh to your child, you can fill in the column that the you are divorcee and can attach the certified copy of the divorce decree to the affidavit and can obtain the passport and other formalities.

1) since custody of child has not been awarded to you and if you want to take child abroad you would need your husband consent . letter from ex husband that he has no objection to you taking child abroad should suffice

2) if husband refuses to give consent you would need court orders to take child abroad

3) you can also apply for your child sole custody before the family court

The NOC so obtained shall be valid for a considerable time provide it is not too late making the authorities to suspect the authenticity.

If you have already obtained NOC, you may apply for visa as per your proposed program

It will be valid during the validity of the visa.