Another facebook question. please answer!?

[Rocky]

From what i understand, your profile is private if set up that way. Anyone's profile you decide to view (friend or not) is also private and the owner can never know who has viewed their profile, pics, videos, etc. Please correct me if I am wrong.

Please include in your answer how you know this. Earlier, someone told me people can see if you have visited their page, but did not provide a reason for why he or she thinks they know this. I am still questioning if there are apps.or other ways this info. can be found out. Thanks.
My question is: Can this change one day? Can facebook suddenly decide they want to reveal everything to everybody no matter how long ago it was.

I do not know if this is true, but I read somewhere that Canada will not even allow facebook because the privacy issues are of big concern.
Thanks ThePurple. Some of that was helpful, but I have to say I still have questions. Does the possibility exist that facebook can sell facebook and all our information with it? In that case all rules now could change later. Is it true they own our pictures? This is why I will not post a pic.

Lastly, I am aware of what facebook posts there, but I am not too trusting and the way it is worded sounds suspect to me. It does not say anything about videos so I am not sure if that is something others can find out about you viewing??

Also when it says, "Recent Activity will never be shown about:", what does that mean?? I do not like the word recent. It is rather ambiguous to me. When I read that I wanted to know more. It needs to be further explaned and should say ALL ACTIVITY regarding Blah, blah and blah will never be shown to anyone anywhere on their page. It will not change in the future. Your info. is always private and will never be sold to anyone. However, X can be seen.