Like: This button is almost worthless now, given all the timeline updates. This just tells others that the person liked your page. If they only click this and nothing else, your posts have virtually no chance of showing up in their news feed. The only benefit this button has is that once they click it, the "Following" option is automatically selected. Once they take away this automatic selection, "Like" will have little value except for Paid Ads targeting options.
Following: This is valuable. This button, when selected, will give your posts the [b]opportunity[b] to show up at the top of their news feed. But in order for this button to work, your fans MUST be sharing, liking and commenting your posts as soon as they become fans of your page. In order to get them to engage early on, you must get them to turn on notifications.
Get Notifications: This is critical to getting people to stick. When clicked, your fans will get a pop-up notification of your new post. This will get people acting on your posts right away, and if they are also "Following", then your posts will start showing up at the top of their news feed.
Interest List: This is not very valuable. When selected, the person puts your page into a list. The few people who do have lists cannot see their list timelines because when they log into facebook, the general timeline is shown first. They must first click their "Interest List" and then they will see that list timeline.
Show in News Feed: This is outdated and has been replaced with "Following"
Ultimately, be aware of the Following option. Right now, Facebook has it preselected as default. At anytime they can unslect it. Make sure you are urging your users to "Get Notifications" and when Facebook turns off the Following pre-selection, make sure you are telling your users to follow you too. It seems ridiculous, but in order to have some sort of engagement in Facebook now, your users need to be Liking, Following and Getting Notifications for your page.
Hope this clears things up. Comments welcome.