One of the fun things about an undergraduate physics program was the steady increase of complexity over four years. Physics 121/122 was essentially an in-depth survey of all the topics, e.g., Newtonian mechanics, optics, electricity & magnetism, thermodynamics, astronomy. Sophomore classes studied each sub-topic in gory detail. Seniors revisited each topic, getting expanded understanding--often rethinking the laws of nature they cemented into place as freshmen. Graduate school continues that process.

As an example, the simple Freshman statements of the the laws of thermodynamics get stood on their head in Physics 431 (I think) where you learn the statistical foundations of those "laws". Nothing is precluded by those laws but the probabilities are vanishingly small. The general, mildly confusing freshman definition of entropy doesn't get any clearer but the equations get much harder. You get a better philosophical framework to address entropy and muse about the "arrow of time", but it's very hard to apply to the comic book level physics of Mr Tompkins in Wonderland (meaning no disrespect to that fabulous book).

I couldn't begin to address your short questions in a short post.

p.s. - I could/would have attempted an answer when I was a freshman, but not as a senior... and certainly not 39 years later.