You should be fine, i returned a F30 with bumper scratches, multiple door dings and a bmw wheel emblem missing. I think chips and minor scratches are considered wear and tear. They will probably repaint the front and rear bumpers anyway. Just be sure to return the car as dirty as possible and at night time
Also, i only returned one key. The guys that take the returns have a lot of leeway. Most of the time they don't care.