Former D3 gymnast here… I should be able to answer any and all D3-related questions!
Academic support services will vary greatly from school to school, and even from team to team within a school. At my school, only a select few sports (not gymnastics) had athlete-specific study halls, but student-athletes were strongly encouraged to take advantage of the resources and services offered to all students (which were often conveniently scheduled to not interfere with athletic practices). In addition, coaches were given their athletes’ grades regularly and notified immediately if any of them were really struggling in a class. I know some D3 schools have more extensive athlete academic programming than this, but it is really something you will need to ask each coach.
As far as visits go, all visits to D3 schools are considered unofficial. You can visit any time you want, as many times as you want, but you will be footing the travel bill. That said, coaches will usually invite their top recruits to take an overnight visit during the fall of their senior year to get to know the team better and see if they would be a good fit with the program. While on that, the recruit’s meals and housing will be provided by the school (but unfortunately, not usually the parents’).
I hope that information is helpful and I am happy to provide more information on the D3 world to those that are interested! I truly had the greatest college experience I could have imagined as a D3 athlete and encourage any gymnast who isn’t getting recruited in 8th grade to check it out.

D3 is becoming more and more competitive every year and is a ton of fun! Check out videos of some of the top teams (Ursinus, La Crosse, Whitewater, Brockport). Last season they were solidly scoring in the 190-193 range and even beating some D1 and D2 teams… all the while doing it for the pure love of the sport. It’s a great time to be a D3 gymnast!