but I doubt it has changed a whole lot since:

You wouldn't be wrong. Minor adjustments to what you've said in regards to point one and two however:

The Academies also draw from the "upper crust" of high schools across america with JROTC program head instructors being able to write recommendations alongside the national level legislative representatives even though there's a limit of recommendations to be handed out yearly per state. From my connections out in the boonies a largly decent chunk of those reccies are partitioned out to service brats of field grade officers to generals but it can vary year by year with more hardcore civvies getting in as well since it's a free ride through a prestigious college if they get in alongside a guaranteed job to whatever bullshit branch they decide upon.

In regard to ROTC, it's divided between pure civvies, service brats, and green-to-gold enlisted trying to become mustangs. The pool of personel is akin to a pyramid in the sense that the first two years of the ROTC program are open to all and do not require signing a soul contract to the military for a free ride through college in exchange for a longer contract in the military (or failing and owing the DOD your student loans instead of DOE). Funny enough, a semester to a year of ROTC lets the average person experience life in the military and how much it can fucking suck and it acts to as a great filter to the pool of potential officers and each additional year further sheds potential officers until you're left with the people that're either plain deadset on joining the military or fucked up and signed the DOD contract and don't want to get crushed by student loan debt from the military. The pool of personnel is a lot more diverse here by virtue of being able to sign your soul to the devil is a whole lot easier.