Any way to auto download or sync all Google+ photos to my Mac?
You can automatically download your photos from Google Photos (I believe Google+ photos end up there, correct me if I'm wrong) fairly easily. It requires a few different steps to get it set up though. Once it's setup, the sync is done for you.


First you have to install the Google Photos Uploader for OS X. 
Next you have to install the Google Drive sync app to sync your Google Drive on your Mac.
Next open Google Photos via your browser and go to settings. From within settings, enable the Google Drive option.

Open Google Drive from your browser and select the Google Photos option. Ensure the settings pane for Google Photos on Google Drive has the Create Google Photos folder enabled.

Lastly, ensure the newly created Google Photos folder in your Google Drive is selected on your Mac's Google Drive settings for sync.


At this point, your photos will sync from your mobile device and desktop to Google Photos, be linked to Google Drive, and sync back down to your desktop for you to pull in to what ever app you want.

Note, as pointed out by @Jer, this will count against your Google Drive storage whereas if you just stored them in Google Photos, you can make use of the unlimited storage. I pay $10 a mo/ for 1TB of Google Drive storage and this works great. I organize all my photos into subdirectories, tag them and manage them via Adobe Lightroom, with Google Drive automatically syncing them to Google Photos on my phone. It also lets me easily select a folder I've organized via Lightroom and share it with other people via Google Drive, instead of having to build out albums and share via Photos.