Congratulations to your grandson! We are on the NW side near the Blue Line, so she takes the Blue Line to Logan Square, and picks up the 52 Kedzie bus (although it runs on California this far north) which drops her directly at the corner of the school. It's 30-40 minutes depending on how well the connection goes, but the kids all know how to text for bus & L arrival times. We carpool with some neighborhood families some mornings but it gets complicated with before school activities, so the kids actually prefer to go on their own. Driving has not been an issue either. We are 10 min from Logan Square and then 10 min south to the school. I have not felt threatened in the least at any time of day or night, but I make a point of staying on Kedzie, rather than coming in from the west -- partly due to traffic.
The kids all come home via public trans (alone or as a group) except after dark, when we pick them up or carpool. There are times she gets home before her Lane friends do because of the congestion at Lane. I know the school is trying to work with CTA to actually coordinate service for students to some areas, where the route is heavily traveled. When she was first accepted, she and I did a trial run of the commute, because I wanted to see where it went and who would be traveling "with" her. I saw lots of tired kids and families on their way to school, and some equally tired adults apparently heading to work. I am happy to answer any other questions if you think of them. If my geography isn't helpful, let me know where he would be coming from and I can try get someone else to help you!