Certainly the first error is due to the malformed URL. In Destination Host you just need to enter the hostname without the rtmp://. As for why it fails when the host is correct, that's difficult to say without seeing more debug. Have you enabled Debug Log for the stream target? Also as I'm sure you know we have a built-in Facebook stream target profile now which handles all of the authentication side of things. I would recommend you use that if possible. It may still be possible to publish to Facebook using a generic RTMP stream target but we don't have any specific workflow for that outside of what you are setting up.
If the problem continues and you have been able to capture more diagnostics then please consider
opening a support ticket and we can take a deeper look.