Follow along with the video below to see how to install our site as a web app on your home screen.
Note: this_feature_currently_requires_accessing_site_using_safari
Damn right G+ helps you to rank in Google!
I made a thread a while back here that you might be interested in about how I did an experiment a while back where I promoted a site using nothing but Google+ and actually managed to get rankings and sales from G+ alone so I can so I know first hand it works.
Of course as krogertek said you want to make sure that you are getting links from and promoting your site on ALL of the big sites for the best results.