For choosing a grad school, you aren't really choosing a school. You are choosing a department, and more importantly, a professor with whom you will be working for the next five years. So, you should look for professors whose research interest you and whose group you would like to join. Also, you should look for a department with a good breadth and depth of knowledge where you think that you will be able to learn from the faculty as a whole (e.g. if there is only one professor doing work that you are interested in, you would not have as much resources as in a school where there are ten professors doing work in your field of interest). Now, as to how to find out more about the professors and their research I would suggest e-mailing professors and their students to find out more about their research, the professors' styles of management, as well as the environment at the school (is it very collaborative? do the students enjoy it there? etc.).