See, to me your reaction seems a little over the top.
I've been following a discussion on No Surprises Policies and how they aren't really realistic and how they seem to treads closely into fear, control and mistrust territory. It seems to me that there is a bit of incompatibility between your need for no surprises and his need for spontaneity. Neither of these is wrong, but be careful that you aren't requiring him to compromise his spontaneity all of the time because that easily feel like control.
Remember that E is a grown adult and doesn't need your permission to make his own decisions. For certain things, yes, he should consult you. But you had already discussed him conversing with her tonight alone. So why does it bother you that he called her on the phone instead of skype? The fact that he came home and told you about it immediately speaks to his honesty and respect for you. Please give him credit for that much.
To me having to have a conversation before making a telephone call feels too much like being babysat.