Yes and no. They have the right to stay in the US for as long as the student visa is active. However, marriage to a US citizen would allow for the Canadian to apply for a CR-1 visa (or IR-1 if they've been married two years or more), which allows for permanent residence.
If the stepfather has legal paper for custody, then the children under 18 are eligible for Canadian citizenship.
That depends on the judge. Normally in the US the mother is given custody. Although there is a trend of joint custody. It's no different than being married to a US citizen. My sister was married to Canadian and she was given full custody. It is always best to work out the arraingment with the ex.
It is possible for a non-US citizen to go to court in a custody case for a child. If one party is an illegal immigrant, they may be subject to deportation.
Probably. Consult a lawyer..if the mom's illegal, that's already breaking the law.
Yes
Yes
Technically your parents will always have custody over you. But if you are a citizen then not really.
Do you live in the US? If so, our Constitution guarantees you the same rights as anyone else. The term is custody. For information in CA see http://www.courtinfo.ca.gov/selfhelp/ then click on guardianship or custody under the Family Section
yes
Individual governments govern their citizen's activities in the Antarctic. For example, if an American citizen working or visiting in the Antarctic, violates a law written in the treaty, that person will fall into the custody of the Federal Bureau of Investigation.
Citizenship is not required in a custody consideration.
Possible, but it's a probate issue.