It's funny...some coaches are very "good" at the whole offering "thing" and some are not. Recently my younger son (who is a lacrosse player) went on a visit to a school that is always ranked with a long tenured coach. We had a good visit but there was no mention of a roster spot offer. As we were being walked out by the assistant coach he was saying how much they think of my son and how they will be waiting on his decision. I had to ask, "Did Coach X offer him a spot?"...and the assistant said yes, most definitely...yet those words were never spoken in the meeting (i.e. We would like to offer you a roster spot.) I just found it odd that a very experienced coach of such an outstanding program could be so vague, because if I hadn't asked we would have never really known if he had been offered or not.
As for the academic money and the coaches...what I have seen with both my sons (older-baseball, younger - lacrosse) is that while the D3 coaches can't really influence the amount of money you get...they can put some pressure on admissions/financial aid to get you an idea of what your merit money would be rather quickly to help you in your decision.
If this is a school your son is really interested in, I would have him tell the coach that he is very interested in their program but can't commit until he has a ballpark idea of the kind of aid he would be getting to go there...however, if the package comes in with a figure your family can live with he will commit. If the coach balks at that idea, I would move on, or contact admissions/financial aid and let them know the situation (you can't commit until you get this number) and see if they can do anything.
Good luck!