Those are just progress messages. You probably have "Echo all commands" checked on (it's under the "History" menu in the script editor) And the warnings about the IBL node are there because you most likely clicked "Image Based Lighting" in the render settings and never bothered to assign an HDRI image to it so it stayed at the default black (which will give you no illumination), Mental Ray is just giving you a heads up.

Also, if you assign a new shader to your wolf and it's still not rendering, post the scene and let's have a looky loo.