What I mean is:
Is it ok for a student that ‘has been accepted to that school’ BUT has not formally accepted… to attend the ADMITTED STUDENT DAY with the goal of further research/confirmations and ask questions???
For my Son, it’s down to a few choices but talking to others (school reps/dept reps/and others who HAVE decided to go there) might help… would asking such questions be considered ‘crude’ by Universities?
Yes, that’s exactly the purpose of Admitted Student Day - at least for the student.
Both my kids had visited schools and narrowed down their choices to three or so - and we then attended each school’s admitted student day to get more information to make the final choice.
The universities know that not all students who attend admitted student day will decide to attend - this is their last pitch to “sell” students on the school. Typically you have much greater access to current students, faculty, and potential peers.
After acceptance there is typically an orientation - at that point it will be only students who have accepted and deposited.
Thanks… it sounds like my thoughts of using the Day to learn more is common!
My D attended an overnight Admitted Student Day - and she learned a lot more about the students - her “mentors” cut the morning class she wanted to go to. 
But she got the admittance letter to her dream school when she got home, so it all worked out ok. Good luck on your visit!
Not only is it OK, think of it as imperative if your child is undecided. In the spring we went to two (many of them are scheduled at the same time- would have gone to three). We had our S narrow down to two and we went with an open mind to learn more and really nail the “feel” aspect. So glad we did. First one , William & Mary, was informative and definitely showed the feel of the school (in his case, not the one he wanted - kind of quiet student body, not really in to sports, etc). He would have gone there over others because of the academics and thought everyone was incredibly friendly, but the second (almost literally) we set foot on campus at Wake Forest, he was sold.
We had been to both previously but this time was much more detailed; sitting in on workshops, eating in the dining hall, speaking to students, etc. He already knew much about both schools and programs. He just wanted to see if he could call a place home for the next four years. It was a great experience and he spent the whole summer enjoying his friends but anxiously awaiting his new journey. Almost the end of semester 1 and he LOVES IT!