Fourteenth Amendment, Debt-Limit Ceiling & President Obama

With a partial resolution of the so-called Fiscal Cliff crisis in the past, the next issue appears to be the debt limit. Traditionally, it has been the authority of Congress to set the debt limit, but, with the House of Representatives and White House controlled by opposing parties, an agreement may not be reached. In light of this likely disagreement, there are legal theorists, law professors, and several politicians contending that a provision of the Fourteenth Amendment allows the President to unilaterally raise the debt ceiling without Congressional approval. The specific provision  is as follows:
Section 4. The validity of the public debt of the United States, authorized by law […] shall not be questioned. 
For the following reasons, most of which textually demonstrate that Congress exclusively handles the finances, this argument is dubious.
First, Section 5 of the Fourteenth Amendment states that Congress [not the President] shall have power to enforce, by appropriate legislation, the provisions of [The Fourteenth Amendment]. Under traditional statutory interpretation, the express inclusion of one thing is the exclusion of all others. For instance, if I state that people with a credit score of 800 receive free financing, an implication is that those with a credit score below 800 will not receive free financing. Applying that approach here, expressly stating that Congress has the power to enforce the Fourteenth Amendment by legislation implicitly excludes all others from doing so, including the President.
Second, it is Congress that has the power to borrow Money on the credit of the United States per Article I, Section 8, Clause 2 (Article I, Section 8 is styled Powers of Congress — not the President.
Third, in Article I, Section 8, Clause 1 Clause Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States. No mention of the President.
Fourth, in Article I, Section 9 — Limits on Congress — No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law; and a regular Statement and Account of the Receipts and Expenditures of all public Money shall be published from time to time. An appropriation is a bill which authorizes the government to spend money. A logical way of reading this provision, therefore, is that the government, by and through Congress, may draw money, but only after passing an appropriation. Further, Congress must keep a detailed accounting of all money. Again, the President is not mentioned.
Fifth, Article I, Section 7, Clause 1 states that All Bills for raising Revenue shall originate in the House of Representatives; but the Senate may propose or concur with Amendments as on other Bills. Thus, while the President may have a say, it must originate in Congress.
Sixth, going back to the pertinent provision of the Fourteenth Amendment, only those debts which are authorized by law shall not be questioned. As demonstrated above, authorized by law is equivalent to Congressional approval. Once fully passed, there is no questioning it.
Fifth, the Supreme Court has recognized that President does not have an appropriations power; rather, it is the President that depends on Congress for funding. See Hein v. Freedom From Religion, 551 U.S., 587 (2007).
Sixth, the fundamental understanding of the Drafters Constitution was that it was Congress who held the pocketbook for the government: The Executive not only dispenses the honors, but holds the sword of the community. The legislature not only commands the purse, but prescribes the rules by which the duties and rights of every citizen are to be regulated. Federalist Paper No. 79.
Seventh, there is nothing in the text of the Constitution, nor is there any case precedent, which stand for the principle that the president may adjust spending (not first allocated by Congress) or the debt unilaterally. Hence, this is a somewhat novel position that is unfounded in Constitutional text and independent of case precedent.
What, then, does this provision of the Fourteenth Amendment mean if it doesn’t authorize the president to raise the debt ceiling?  As interpreted in U.S. v. Perry, it is confirmatory of a fundamental principle that debts already incurred cannot be questioned. Accordingly, debts arising out of past expenditures cannot be challenged for their validity; it does not speak to prospective spending, as the President would argue if he tries to raise the debt limit unilaterally.