This is a long one

Article II - The Executive Branch

Section 1 - The President
The President and Vice President stay in office for 4 years.
Election: Each state appoints Electors. The number of Electors is equal to the number of Senators and Representatives of that state. A person who has an "office of trust"(Representative, Senate, etc) cannot be an Elector. The Electors vote by ballot for two people (who can't be both in the same states as the Electors). They then make a list of everyone voted for and the number of votes for each and send it to the President of the Senate. The President of the Senate opens the lists and counts the votes in front of the Senate and House of Representatives. The person with the most votes becomes President. If more than one person has a majority and equal votes, then the House of Representatives chooses by ballot one of them to be President. If no one has a majority, then the top five are voted on again by the House. (Previously, the Vice President was whoever came in second place for President. Now, the Vice President is voted for separately.) If the House does not choose the President when they need to before march 4th of the following year, then the Vice President acts as President. If the vote of the Vice President doesn't have a clear winner, the Senate votes for who will be Vice President.
Congress can choose what day is voting day, but it has to be the same through the USA. You have to be a natural born citizen, 35 years old, and lived in the US for 14 years to be President. The terms of the Office of President and Vice President end at noon on Jan 20th and the Senators and Representatives at noon on Jan 3. Congress meets once a year at noon on Jan 3 unless by law they appoint a different day. If the President Elect dies before starting his term, the Vice President Elect becomes President. The Congress can declare who shall act as President if neither the President or the Vice President qualify. If the Vice President's spot becomes vacant, the President can nominate a Vice President who then is confirmed by a majority vote by both Houses of Congress.
A President can write to the President of the Senate and Speaker of the House of Representatives and say he is unable to do his duties. Unless he writes another statement to the contrary, the Vice President becomes Acting President. If the Vice President and a majority of the principal officers of the executive departments write a declaration to the President of the Senate and Speaker of the House that the President is unable to do his duties, the Vice President becomes Acting President. But if the President then writes a declaration that says he can do his duties, he resumes his powers unless the Vice President and majority within 4 days again write to say he can't do his duties. Then, the congress will decide the issue. They must meet within 48 hours. They have 21 days to determine by 2/3 vote of both Houses that the President is unable to do his duties. the Vice President then continues to be Acting President otherwise the President keeps his office.
The President will receive a paycheck, but that cannot be increased or decreased during his term, and he can't receive any other pay from the US.
When he is sworn into office he must say "I do solemnly swear that I will faithfully execute the Office of President of the United States, and will to the best of my ability, Preserve, protect and defend the constitution of the United States."