Propionic is an interesting consideration because Swiss Gruyere has no holes, and French Gruyere styles like Beufort or even Comte also have no holes. I think with raw milk, you will get some naturally occurring propionic, which contributes to CO2 production and flavor. The extra propionic in some areas makes more of a Emmethal or Swiss/Jarlsberg type cheese. Similar history and technique. I would not add priopionic to a base gruyere recipe unless I was going for a baby swiss or added depth.
This recipe should produce a Gruyere style cheese, and of course can be modified to fit your flavor and style needs.
I don't think it matters when you add CaCl2 if the ions are diffused by the time you rennet, because it is at rennetting that CA++ makes a huge difference. I've seen no difference in my sets and usually do not add CaCl2 unless it is winter milk or the balance is off for some other reason (feed, lactation cycle, etc)