I'll now answer all three items, and NO offense is meant.
The answers all come from the US Code, which codifies all items in the Constitution, like Article 2 Section 1, and contains all other Federal Laws passed by congress.
You're correct about his father, he was an immigrant, but his mother was a US Citizen. The US Code addresses all three question:
(g) a person born outside the geographical limits of the United States and its outlying possessions of parents one of whom is an alien, and the other a citizen of the United States who, prior to the birth of such person, was physically present in the United States or its outlying possessions for a period or periods totaling not less than five years, at least two of which were after attaining the age of fourteen years
Now some will respond that Paragraph 'g' was amended, it changed the years noted which effected Barry's mother's status and his as a citizen. THAT'S TRUE, it was amended, in 1986. But it was not a retroactive amendment (which would be an ex post facto law, and Unconstitutional. In short, it only effected those born after 1984. And not Obama who was born in 1961. (1)
Section 1401: Nationals and citizens of United States at birth
The following shall be nationals and citizens of the United States at birth: (a) a person born in the United States, and subject to the jurisdiction thereof
(this takes care of any legal questions if he was born in Hawaii)
(this takes care of any legal questions if he was NOT born in Hawaii)
He could have been born anywhere and as long as his mother was a US Citizen, so is he.
Here is additional legal reference on Citizenship: Constitutional Topic: Citizenship
(1)Notes on 08 U.S.C. § 1401 : US Code - Notes 1986 - Subsec. (g). Pub. L. 99-653 substituted "five years, at least two" for "ten years, at least five".
EFFECTIVE DATE OF 1986 AMENDMENT: Section 23(d) of Pub. L. 99-653, as added by Pub. L. 100-525, Sec. 8(r), Oct. 24, 1988, 102 Stat. 2619, provided that:
"The amendment made by section 12 [amending this section] shall apply to persons born on or after November 14, 1986."
I believe the US Code cited above should end any 'Natural Born Citizen' questions.
Now, why Barry's spent $1 Million+ fighting this in courts beats the heck out of me. He should just ref 1401 and end it.
ps: Excuse the tardy reply. I'm on my backup computer and its very slow. I feel like that turtle in the Comcast ad.