this is very simple and should like all the loaded like buttons http://pastebin.com/CUhS9vq4, it also unlikes whatever was already liked though, since fb doesn't seem to change the class.
That's not going to work. Facebook will block you from liking on account of "going way too fast". Calling a sleep() function after every like might help...
So i guess the script would need to include some kind of gradually escalating random "like" increase.
You can actually use this method on LinkedIn to endorse all of your friends, and because it offers more results, you can set an interval to endorse infinitely. My LinkedIn friends all hate me now because they've been endorsed for random things.