Hey there!
I attended NASS last summer, and it was way better than I expected it to be; however, that may be because I hadn't really considered an SA seriously as a college option before then. I went in completely blind, so I'm pretty glad that things worked out.
Every morning, everyone wakes up at 5:30, sometimes even before. The detailers will barge into your room and rudely awaken you from your deep slumber, playing "Mary Had a Little Lamb" at obscenely high volumes and yelling into a megaphone. You need to get your booty down into formation ASAP, and by that, I mean, in the span of 2-3 minutes. Basically you only have enough time to get changed and grab your bag and go. Then you go to PT with all the other companies, which I found pretty easy, actually, even when we had the SEAL come in. After, I dunno, 45-60 minutes later, you'll have enough time to get washed up and shower and stuff before going back to formation, and then breakfast.
On the weekdays, you'll have the classes you picked, for I think 1.5 or 2 hours each, with lunch in between. I forgot the exact schedule, so someone could probably fill you in on that. Some of the classes are fun, some are boring, and I don't think you can change that. I've heard of people sneaking into other classes though. Like martial arts. I heard that one was pretty enjoyable.
After classes, my memory gets a bit fuzzy. In no particular order, your squad leader will most like suggest sports against a rival squad, or choose to sit you down somewhere so you can ask questions, get to know each other a little better, etc. Every day, your squad leader will tell you to write a sort of reflection/summary of your day. You'll also go to dinner, and possibly sit at Alumni Hall for some presentation (I remember that there was one about USNA sports, and you got to go speak to the coaches about stuff you were interested in afterward). Somewhere scattered in there is drill practice, as we didn't really have a set schedule for that. Most of the time the detailers were just like "Eh, we have some extra time and it's not too hot outside, so drills it is."
At night, just before taps, sometimes the company leader will have a chat (can be good or bad) with y'all, and on one day they'll let you ask questions about what life is like at the Academy. Some other day, your company will be split up into guys and girls, and you'll be able to have some female bonding time. This can lead to some pretty weird conversations, but all in all, it's fun. At the end of the day, you'll be called back into formation, or be told to stand along the wall, and "count-off". If your company leader decides that you were all good little boys and girls that day, you'll have the honor of singing the school fight song. Then comes taps. Wash up and hurry up and get to bed, because you're waking up at the crack of dawn the next morning. By the way, you're not allowed to close your door unless someone's showering or changing.
Sea Trials happens on the last day. I was mostly out of commission due to aforementioned injury. Someone else could probably provide a lot more info on that.
Anyways, throughout the week, you'll be given a handout with a bunch of information, like Navy/Marine Corps ranks, the mission, etc etc that you need to memorize. Indoc is right after Sea Trials, so you'll probably be physically exhausted, and now the detailers are gonna make sure your head is in working order as well. If you screw up, they won't do anything except scream in your face and make you do push-ups. Looking back on it, it was actually pretty comical, but at the time I was plenty nervous/scared.
Also, don't be worried if you feel like you're physically not fit, as I sure as heck wasn't. Yes, on the second day you will take the CFA, but it's honestly not a big deal. I ran my mile in 9+ minutes due to a hamstring strain and still was "very qualified", because I did pretty well on pretty much everything else. You said you did research, so I have a good feeling that you already know what the CFA covers. It's a good idea to be prepared during NASS so you won't have to redo it later on.
There is time Sunday morning for religious worship. Last year, they only had Catholic mass available, I think. USNA normally offers a lot more in regards to religion, so I guess it just depends on your session. If you're not religious, then would be a good time to catch up on the indoc stuff, or get some extra sleep.
Other than that, I feel like I've covered most of the major highlights of NASS. It was truly a wonderful experience, and I hope it will be for you, too. Hope this helped
