Can I control how google accounts get synced? Mobile vs Wifi
Syncing Google Play Music doesn't actually download the music: it just updates the list of what music you have. Music streams, caches, or downloads when you start to play it, and you can control that using the settings inside Google Play Music itself: Download via Wi-Fi only and Stream via Wi-Fi only.

In the same way, you can control when Google+ "Auto-Backup" backs up photos and videos, using the settings inside Google+. From the settings menu, click Auto-Backup, and click Back up photos and Back up videos to select when they're synced.