[Plugin: Infinite-Scroll] Cannot find Infinite Scroll in WordPress Twenty Ten Theme

According to this article: http://en.support.wordpress.com/infinite-scroll/

it seems that many themems have infinite scroll installed in them, including twenty ten, which is the theme that we are using. However, we are unable to find it in settings>reading so we download the plugin

#1.Is the plugin same as the built in app?
#2. How does infinite scrolling affect pageviews? does it count the entire full load of posts as one view or each load more is considered a new page view?

http://ww.wp.xz.cn/extend/plugins/infinite-scroll/