How can I update multiple MacBook Airs from Mavericks to Yosemite utilizing ARD?
You should be able to use Apple Remote Desktop to copy the macOS Installer application to the Applications folder on every client Mac, then send the following UNIX command as root:

/Applications/Install\ OS\ X\ Yosemite/Contents/Resources/startosinstall --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --agreetolicense --nointeraction


This command starts the in-place upgrade action to OS X Yosemite. It may take some time for the entire process to complete, but it doesn't require any user interaction.