Are you currently living in Dublin?
The commuter service to Mullingar is superb compared to a few years back and I believe is only going to get better. Very suitable if you work close to connolly/tara or pearse. The morning train takes 1:30 hrs and evening train home takes 1:05. In morning trains leave at 6:50 or 7:30 - express evening trains leave at 5/6/7pm.
With regard to schools, I am not from the mullingar area but as with any provincial town you will have a selection of schools just outside the town that you should look at.