Fenway makes a great point about leading with academics; it's logistically so much easier to start with a pile of guys who have a shot of admission (as athletes) and find the baseball skills than the other way around.
With that thought in mind, on all campus visits son had a sealed envelop of grades and scores (updated as he aged) to give to any baseball coach he ran into; on every campus visit on our college route he would take a whack at seeing the baseball department (alone). Tail end of soph year, he hit an Ivy baseball office during a visit, coach was in, coach made positive comments - fast forward and that's where he went. (Before the visit, he had had no prior contact with coach or school.)
On velo, i think coaches look at HS "sitting" velos for short stints (a couple of innings); college pitchers - if knowing they are going a couple of innings - have higher velos and can maintain for longer. I know my son at the end of HS was "sitting" 90 for 2 innings; by the seventh he was 85 - 6. In college he could keep up the velo through 7 and go 91 - 3 for a single inning.