saty with him and take him to court to force him to pay child support
yes.
Unlikely in most countries.
I believe the answer is YES as long as the 21 year old proves to be capable of doing so.
It's perfectly normal for a 23 year old to be intrested in a fifteen year old, but they can't date until both are eighteen (it's against the law).
You seem to be having trouble figuring out which word is the noun that needs to be the plural. Which thing do you have more of - twenty, year, or old? Twenty years is the modifier for old. You have two twenty year olds.
No; that is child molestation.
You should go to the police and turn him in for statutory rape, he will go to jail and you will get a lot of money to help you and your unborn child.
No, the girl must be 18 years old.
No. You are not emancipated.
No, but it is certainly rude.
No, because even if you are in love with him; he cannot marry a minor it is illegal.
No, it most certainly is not legal! It would be a crime.