Re: Google Plus
When you have a gmail account, that gives you all google services.
Yes, once photos are uploaded to google drive, you can then delete them from the phone.
G+ (google plus) will also back up all your photos. You can set G+ to only upload while on Wifi or to use data.
G+ is awesome, don't think of it as a facebook wanna-be because it's so much more than that.
G+ has a feature that is called auto awesome. If you went to a party and took a bunch of pics, it will email you and tell you to check out the auto awesome photo "slide show" that it puts together for you.
Also, G+ lets you follow "communities" or your favorite sites.
I love cats and follow 2 cat communities. I follow several tech sites and android and apple communities as well.
It basically becomes a news reader full of stuff YOU like. I love it. It's the FIRST app I install on my new iPhones and its part of the android OS so its there when you turn it on.