Regarding FinalIK, disabling the finalIK component is intentional because the component is manually updated from slate. Disabling the component avoids it being updated twice (one from slate and another from finalIK “Update” method). With that said however, I am not exactly sure of the problem you mention. Do you have the FinalIK Slate Clip in an Action Track that is above any other animation related tracks like for example above Animator Track?
Also regarding custom “Character Look At” clip, can you please post a screenshot of your cutscene?
There shouldn’t be a problem with the Character component being attached on the root (as a matter of fact that is how it was designed to work since it searches for Skinned Mesh Renderer within all the children of the gameobject attached.