I don't thing that will make much changes to your rank, but yes google definitely will index few more pages for your website, so if lot of activity happens around the same content this will improve the rank.
Well it would be pay to make an account using Google+, you can also increase the credibility of your site with this feature.
Google+ is not the greatest place to promote your business , But it is an excellent place to promote yourself. I would get in Now and build you personal profile, so when the business side is launched your ready. Once the business features launch Google+ will really build fast. Be ready for it I say! Oda