So the first one is characters movement. If click on any entity before clicking on the scene character start moving weird.
Is seems the actor is still performing the smooth animation transitioning while already running. Reduce the animation transition time from idle to run.
Second is scene loading. When switching from a certain scene first loading a scene and after about 1 second character is showing.
Check your scene_init.script. There's probably some command which blocks scritp execution prior to setting actor's initial position.
The third one is shadow. In one scene shadow's casting on camera just like on walls...
That's by design... You'll need to tweak the shadow direction in the scene.