About the camera issue:
I guess you're using the templates.
That your model disappears has nothing to do with the camera.genius actually.
The problem is, that the camera moves into a solid block ad though does not display any models anymore.
Now if you turn more left the camera moves out of the wall and you see your level from the outside.
The only way to fix this is to add collision to your camera.
How to do this?
Either ask in the templates forum if there is a collision for the camera available which works with the templates, or you script your own movement and camera system.
You could also ask in "User Requests" or the "Job Offered" forums if somebody is willed to do the scripting for you, if you are not that "advanced" in C-Script.