Hamilton's program was more state capitalism than true mercantilism
It's actually known as neo-mercantilism...basically old mercantilism with more refined-sounding arguments, or mercantilism that emerged in the wake of the Wealth of Nations as an attempted counterargument. Hamilton is actually considered one of the founding fathers of the neo-mercantilist school, along with Frederick List (who he directly inspired). His 3 "Great" Reports are considered to be some of the first formal attempts to rebut Smith, particularly the Report on Manufactures.
Capitalism NEVER developed as Free Markets and there has never been a capitalist system which was not heavily influenced by the state.
Oh really? Tell that to Hong Kong in the Cowperthwaite era of the mid 20th century.
Don't pretend that the core of his opposition to the national debt assumption program was not the land speculators whose schemes depended upon the debt remaining cheap.
Actually, the most vocal opposition came from the states that had already paid off most of their debt obligations and objected to assuming debt from the states that had been financially irresponsible over the previous decade. In other words, bailouts. Funny how 200 years later we still have the same problem.