Facebook – Archive only reaches back to around mid 2012

I've tried the feature too (if someone hasn't: here's a tutorial), and my experiences are these:

• Yeah, likes and comments to my statuses etc. are mostly missing from older posts (say, older than mid 2008).

• As for messages, they definitely are there. (Each and every message, it seems, since I joined in Sep 2007.) If you open the index.html on the top level of the zip, it's the last item on the left-hand menu:

My guesstimate is that if old comments etc. are missing, there were technical reasons for not being able to retrieve them all, instead of any change in "policy" or intention. But if messages really are completely missing for you, that does sound strange.

Liking a page does not grant the page admins access to your status updates, friends list, or other information on your wall or profile if it is not already visible to Everyone. They will have access to your name, profile picture, gender, networks, and Facebook username and uid; these are always visible to Everyone.

Additionally, the page admins have access to aggregated demographic information on their entire fan base. This includes the percentage of fans in each gender & age range, and the number of fans by country, city, and language setting, but only for at most the top 20 countries and cities and only where the number is significant. The demographic information does not identify individual fans, and is not available at all for pages with less than 30 fans. See this blog post for an example of what is shown.

As you noted the page can post content to their Wall which will appear in your News Feed, however you can use the X in the upper right corner of any such content to hide all of the page content from your News Feed and still Like the page. The page can also send you Updates, which appear in a subtab under Messages.

Facebook has a history of introducing changes that have unannounced privacy impacts, so keep that in mind and do not count on their current practices staying the same. In fact you can be sure that there will be changes over time.