I commented on someone’s picture and it was posted on my wall. Can everyone see it ?

Only people that can see what you wrote are those who can see the picture you commented on. So, it comes down to who the owner of the picture... Read more »

How can I find out my or someone elses Facebook ID number ?

To find out what your Facebook ID number is after you have changed your Facebook URL to a profile name – use the User Graph interface : http://graph.facebook.com/first.lastname [this... Read more »

I’ve been automatically added to a Facebook Group that I didn’t join, how did that happen ?

Facebook recently changed the way Groups work. Before when someone saw a group they thought some of their friends would like, they could select the names and “suggest” it... Read more »