No. Under the law in effect then, she had to have been 19 years old.
Depends on whether she was an unwed mother when obama was born. If she was unwed, then she only needed to have been physically in the US for 12 months prior to O’s birth (not immediately prior). If so he is a citizen at birth.
Per the State Dept. Foreign Affairs manual, it has never been definitively determined whether a person born abroad to American citizen is considered, natural born with respect to eligibility to be POTUS.