I have a garage that was built out from a carport, so all I have are rafters, not trusses. I really want to insulate the ceiling because it gets really hot/cold in there. The big question I have deals with airflow. I am getting my roof replaced and my initial plan is thus:

1. Have the roofers add a ridge vent above the garage
2. Add rafter vents between each rafter up to the ridge vent, pulling air from the eves.
3. Put in batting insulation over the rafter vents

Is this overkill?  Do I need the rafter vents/ridge vent?  Is there a better way?

TIA