it is 45 mins on train from helensburgh to glasgow queen street, it would be less than 30 mins to clydebank. ( you could drive to cyldebank in 30 mins might be longer at 9am)
I don't think cycling from helensburgh to clydebank daily is feasible
lomond school is private and goes from 3-18 it is in central helensburgh
hermitage primary and rhu are generally thought to be better than the others but the others are not bad schools, the high school /academy is fine certainly in top 25% in Scotland but not the top 10%