Two citizen parents? What if one or both was naturalized? What if both were born here, but the grandparents were illegals? Or naturalized? Where's the law on the subject?
The fact is, "natural born citizen" has never been defined by Congress or the courts. Therefore, one must assume it means "citizen at birth", as opposed to "not a citizen at birth but became one later via naturalization (a legal process)". Assuming Obama was indeed born in Hawaii, he was a citizen at birth for sure, per the 14th Amendment, and is therefore a natural born citizen.
That is correct. A Supreme Court ruling is needed. Regarding your questions about naturalized parents etc., please search for and read the thread titled "Obama's Presidential Eligibility - An Introductory Primer" written by Stephen Tonchen and posted by me. Please post your comments and questions about it on that thread.
No, we need not, and should not. Congres has no power to define Constitutional terms. They mean what they meant when the document was written.
But logically anyone whose citizenship rests on a law passed by Congress, except insofar as that law is duplicative of the definition at the time the Constitution was written, cannot be "natural born", because Congress only has the power to "Establish an Uniform Rule of Naturalization".
We can't have Congress redefining the terms in the Constitution, unless that document explicitly gives them the power to do so, otherwise much mischief could they make.