II have a nephew who is going to be 18 in june, he really want to live with me but he has one more year to go?

Since grandparents have legal custody, it will continue until nephew is 18 years old.

Can i take legal action against someone who threatens to cause harm to me and my unborn child?

You can ask order of protection against your neighbor to stay away from your children.

How do I get child support?

It is not clear if you are divorced. If you are divorced, you can file for child support.

I live with my wife; getting divorced. She has custody of a 17 y.o. who was impregnated by a 19 y.o. & I don't want him here.

You might not be successful because 19 years old is there with wife's consent.

You can ask to modify child custody or visitation based on behavior of kids father's behavior.

How can I keep my child's father away/ keep him from taking full custody?

Child custody is based on best interest of child. Child's father behavior is definitely one factor to take into consideration but not determinitive.

Can disability payments from non custodial payments affect custody rights?

Changing financial situation affects alimony or child support but not custody.

You can request for postponement because of drug rehabilitation.

You can file for contempt for non-payment of arrears. You can also file for upward of child support if his income changed by 15% or more assuming...

Collecting alimony from ex who deceided to start an LLC company with his mother stating he has no money?

You can enforce order by registering in Florida.