You learned alot during your short time here!
The roofer doesn't know the proper answer for the ridge vent plus the turbines, but he did provide a valid working scenario with 100 % vented soffits or Smart Vent as Augie linked to and also 100 % continuous ridge vent, preferably, Shingle Vent II, with external wind deflecting baffles.
Read the installation instructions yourself and ensure he is using long enough nails to secure firstly, the ridge vent down and then the shingle ridge caps. I use 2 1/2" hand roofing nails for the ridge vent if the old shingles are removed, but 3" would be acceptable too.
For the longest life of your new shingle roof investment, please do yourself the favor and install the intake and the exhaust vetilation 100 % continuously, and close off the gable vents and eliminate any thought of adding additional whirlybird or turbine vents.