Yes, Social Media Play a crucial role in Search Engine Optimization. Social Media gives you traffic as well as High Domain Authority and Page Rank.
The latest version is Android 6 Marshmallow, which will gradually become available for more and more devices over the coming months. Lollipop is 5.x, and KitKat is version 4.4.x, with 4.3, 4.2 and 4.1 all coming under the codename name Jelly Bean.