I wouldn't cover the metal plate on the door with vinyl. Its got the logo on it, I'd just put it back on over the vinyl. If you wanted to replace the woodgrain with something else then go for it. Carbon fiber, paint, gold leaf...etc.
Not sure what you mean about a insert along the red line.... the groove is filled now right? so what will the insert be inserted into?
I'm really anxious to see how it turns out.