Mama, as I have always understood the Commerce Clause, it was there to give FedGov the authority to tell New York that it cannot impose a duty on goods coming in for sale from Pennsylvania or a tariff on goods being transshipped from Vermont through New York into Pennsylvania. In other words, to ensure a level field with respect to State GOVERNMENT actions involving trade and protectionism at that level. The Founders NEVER intended that Congress or the Executive have authority to ban goods, to impose any sort of regulation of BUSINESS or industry whatsoever. It was only to ensure the STATES THEMSELVES played fair.
Exactly right, and that's why she said "ENTITIES" - to indicate the corporate States alone.
As far as the internal power of the clause goes, that's true.
Externally, the clause gives the fed government the authority to regulate commerce coming in [income] from foreign nations.
Goods coming from England for example, could be directed to different ports in order to distribute the taxes 'among the several States'. [Contrary to popular belief, the fed government doesn't have exclusive jurisdiction at the ports, they share it with the State where the port is located. This is called concurrent jurisdiction.]
Incidentally, this power could also be used as a punishment mechanism on a State for noncompliance with the Constitution by allowing the fed government to AVOID ports in certain States, thereby denying state their share of the revenue from importation taxes.
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§ 1075 The constitution is one of limited and enumerated powers; and none of them can be rightfully exercised beyond the scope of the objects, specified in those powers. It is not disputed, that, when the power is given, all the appropriate means to carry it into effect are included. Neither is it disputed, that the laying of duties is, or may be an appropriate means of regulating commerce. But the question is a very different one, whether, under pretence of an exercise of the power to regulate commerce, congress may in fact impose duties for objects wholly distinct from commerce. The question comes to this, whether a power, exclusively for the regulation of commerce, is a power for the regulation of manufactures? The statement of such a question would seem to involve its own answer. Can a power, granted for one purpose, be transferred to another? If it can, where is the limitation in the constitution? Are not commerce and manufactures as distinct, as commerce and agriculture? If they are, how can a power to regulate one arise from a power to regulate the other?
It is true, that commerce and manufactures are, or may be, intimately connected with each other. A regulation of one may injuriously or beneficially affect the other. But that is not the point in controversy. It is, whether congress has a right to regulate that, which is not committed to it, under a power, which is committed to it, simply because there is, or may be an intimate connexion between the powers. If this were admitted, the enumeration of the powers of congress would be wholly unnecessary and nugatory. Agriculture, colonies, capital, machinery, the wages of labour, the profits of stock, the rents of land, the punctual performance of contracts, and the diffusion of knowledge would all be within the scope of the power; for all of them bear an intimate relation to commerce. The result would be, that the powers of congress would embrace the widest extent of legislative functions, to the utter demolition of all constitutional boundaries between the state and national governments. When duties are laid, not for purposes of revenue, but of retaliation and restriction, to countervail foreign restrictions, they are strictly within the scope of the power, as a regulation of commerce. But when laid to encourage manufactures, they have nothing to do with it. The power to regulate manufactures is no more confided to congress, than the power to interfere with the systems of education, the poor laws, or the road laws of the states.
Joseph Story, Commentaries on the Constitution