My 2017 went through a similar process with a number of D3 academic schools. There is some great advice here in this thread. To summarize, in terms of what 2017 experienced, I would emphasize:
1. Do your unofficial visit during the time the team is practicing in the Fall. Ask the coach when that is and tell him you would like to watch a practice/scrimmage. There is a huge value in visiting in the Fall before applications are due and you can assess the school in session and watch your future competition on the field. And visiting then confirms your interest is sincere.
2. If the coach really likes you, he will offer you a "guaranteed" roster spot but will pressure you to apply Early Decision (ED). Do it only if you are 100% certain you want to go to this school and your family can afford it. You can consider other schools and get quicker admission decisions by applying Early Action. If he really likes you, he will wait (especially since they are already got a positive pre-read on you).
3. The only way you can know how this school rates is to visit other schools and talk to other coaches. My 2017 had 9 such visits (4 were over one long weekend) before deciding his school in late March. He was diligent in considering all of the main factors and really adopted the mantra "if the baseball does not work out, could I see myself happy at this school for four years." Finding a match for his interest in engineering combined with baseball necessitated that many visits for the right fit.
4. Remember there is no athletic money available at the D3 level, so do your research on the amount of merit money that might be available, if any (some of the elite academic do not offer merit money because all of their students are elite). If you think you might qualify for financial need-based aid, get on the FASFA application the minute it opens (I think Oct 1st). Knowing how much assistance you can get toward each school is a critical part of most kid's final decision process.
5. Keep working on your game. If you are looking at D3 schools, there is no sure thing. D3 coaches recruit later and cast a wide net because they have to. They can change their mind all the way into your Spring season Freshman year before you really have a roster spot.
6. Congrats on your academic credentials. But a higher GPA in your Fall semester will help your cause for admission and aid. Maybe even retake the ACT and score even higher? Some schools match their aid to the level of ACT score. 2017 saw merit amounts increase up to $2K more by scoring two points higher on his retest.
As others have asked, let us know how this all works out. Lots of kids are in similar situations and would learn from your experience and decisions. Good luck.