Even if it is true, Trump as President has broad authority to do it. It's not illegal. About the only thing this really does is potentially upset an ally and/or out a channel for gathering Intel to the Russians. Again, that's only if it's true. It's far less damning than outing Valerie Plame.
This is true. I believe he has the power to classify or declassify any intelligence. So no law(s) were broken here. But as you said, it's a matter of liability. That's my main point of contention.