What you have from St. John's is one of their probationary admits... it's not that hard to pull a B- or better in the summer class, and it does lighten up your load for the fall semester. Several people in the PT program were admitted under those circumstances... then again, I wouldn't know about any that weren't offered such admissions. The curve is fairly generous... I *believe* that only about 20% of the curve is below a B-.
As for recieving any sort of award letter, I don't think they send them out seperately... I recieved mine from Hofstra & St. John's in the acceptance letter. With the probationary admit @ St. John's, you can pretty much forget about getting any sort of scholarship money there. As for Hofstra, maybe you can get a few bucks from them.
As for whether you should go w/ St. John's or Hofstra, you should probably visit both schools and check them out for yourself. Hofstra is the Long Island law school... so don't expect much in the way of job opportunity outside of Long Island. SJU has more connections within NYC (and strangely, Miami), so you do have more options there. Take a look at clinical opportunities as well. I will say that Hofstra has/had some good teachers... one of SJU's Contracts professors was formerly at Hofstra and one of the Property professors is a visting professor from Hofstra.