As far as in the perimeter, Brookhaven is pretty nice, depending on the specific neighborhood. I know a decent number of people that live in the area and like it. Public schools are a mixed bag overall in Dekalb County. I can't speak about Marist from experience. I know a few folks with young kids that go to OLA (another Catholic school nearby) and like it.

Generally speaking, living anywhere in the perimeter, there is a higher chance of crime than outside the perimeter. Brookhaven has it's own police (instead of through Dekalb County, etc.). You can look up a crime map on their website to make more informed decisions for yourself.

Driving would likely be more like 30mins without traffic and 1 hour with, again depending on where in Brookhaven you live.