no
A sexual relationship? Legally, no. Can you be friends? Yes.
Yes!
It depends what you do in the relationship and where you live
Yes.
Yes
It depents on the country you are from
It is not illegal.
Not until you legally turn 18.
No, Not unless you are comfortable with the fact that you are playing a part in breaking up that 17 year old partnership. (Think how you would feel if you were the woman who has the 17 year old relationship).
yh but whos the 18 yr old a girl or boy??
no. not that im aware of.