Everything was going well, when I noticed that facebook disappeared from the email+accounts, could it be related to the Store and it's outage?
You need to install the FB app now to restore similar functionality (which can be done straight from the People hub. I say 'similar' because going into posts just drops you into the Facebook app. It's still integrated, just a little differently. Just turn off message notifications if you have the Messenger app installed or you will get double notifications.