How much does it cost to advertise on facebook?

What does CPM & CPC mean? Can anyone who has advertised on facebook describe how much it cost you overall? Also, is there anyone who can mention if facebook advertising (and the specific type of facebook ad – social ad/etc, age group) was positive or negative for them in their ventures? I’d really appreciate any responses to this, thanks.

What happens if you deactivate your facebook account?

If you are an admin of a page you created on facebook, does that mean that if you deactivate your account, then reactivate it you will no longer be an admin of that particular page on facebook? Or will you always stay an admin? Thank you!
I deactivated my facebook page a few hours ago, and about 10 minutes I reactivated it, but it doesn’t show that I am an admin of the page that I created. Will I no longer be admin?