The hand signifies that the Instructable is a collaboration, and more than one person worked on it. Here's an example of a collaboration.

RSS is abbreviation of "Really Simple Syndication". Google it. L

someone else can give a better description... its pretty much a subscribe button you just subscribe to that rss feed through a site like google reader and it will automatically update for what ever that feed is on Since we are on forums, ill use that as an example. In the featured forms list, there is a rss icon I would click that and input it into google reader. Then the next time theres a new featured forum, I will get notified from google reader to see what the storys would look like, just click the icon

I'm not entirely sure. I'll tell you who does know, though, google and wikipedia. I recommend starting searches to questions like the above one there