Do family law contracts between ex-spouses ever get voided based on common contracts defenses?

There are so many variables it is impossible to give you a yes or no without further discussion. You really should pay for a consultation with a...

Can my daughter when she turns 17 choose, without court intervention, and without her father's consent,to live with me full time

You can file to modify the order. Your daughter does not get to make decisions until she turns 18. However, her opinion will be important.

What options do I have to change the custody agreement in this instance? Is it futile to try?

Hire a lawyer and file a modification. The best interest of the child will control, plus there will be a strong push to have the children together.

What legal action can he take to have it ordered that I send our son to CA this June? How do I revise the child visitation?

Frankly, it will cost you far more to fight this than to do it. By thousands of dollars, and I doubt you would win. Postpone the move by a...

How can a prisoner initiate child support in order to see his son?

Help him hire a lawyer in the county where the child lives.

How do you prove that you were not separated for a particular duration during divorce procedure?

It doesn't matter. At all. Don't worry about it. Texas doesn't have legal separation, it was not a break in the marriage from the legal point of...

How do I get supervised visitation and do I need to prove the father unfit?

Your question shows that there are still some gaps in your understanding of your options. You really should sit down with a lawyer.

What can I do if a custody agreement was read front of judge by opposite party and it was completely different then my attorney

You need to ask your lawyer or hire a new lawyer TODAY.

How do I prove my husband has committed community property fraud?

Hire a lawyer. This is not a DIY case.

You don't mention your lawyer. Hire one if you don't have one. That is the single best thing you can do to protect yourself and your children.