It is legal if the 17 year-old's parents give permission to get married. Without their permission it would not be valid.
No. It isn't legal for a 16 year old to have sex with a 20 year old in California, so living together is out of the question. You can get your parent or guardian to sign papers to allow the two of you to marry, but not live together unwed.
In the USA an 18-year-old is a legal adult.... so yes, a 19 year old can marry whoever they want.
Yes.
Yes.
Yes with parental consent.
Not without parental permission.
Not without parental consent.
If you live in the US it is.
I wouldn't. And it will require parental permission.
yes they can but only with the consent of their parents.
No.
yes