I haven't got a reversing camera but if I were buying a new car and had young kids, I would definately get one!
If looking in mirrors were that effective, My son would not have reversed into an upturned shopping trolley that someone had abandoned in the dip behind our garage. Neither of us saw it when we opened the garage and although he stopped as soon as he felt he had caught something on his bumper, it really brought home to me how easy accidents involving reversing vehicles and littlies could be.
I can't comment on who would be best to fit the camera but if you have a warranty on the car, would it be affected by getting someone other than the garage to fit it? Just wondering.
Here's to many years of safe, enjoyable driving in your new car :)