Well, as it's not near any other body part, any'O good paintshop can do a filling and spraying job without removing the bumper. What they do is fill and grind the scratch, spray it with silver paint, gently easing of with the paint, and respray with clear lacquer, a bit of buffing a few hours later, and you want be able to see where they started to respray it.
The Stone chips is a totally different matter. No matter how careful you are. You can allways see a black edge around the places where you put droplets of paint in the imperfections left by them bugger all stones. Anyway, leaving them as is is no good idea either.
I have developed a technique to make stonechip repairs almost invisible. To bad it does'nt work wonders on light metallic paints. It's better than the regular jobbie, but it requires sanding with 2000 grain wet sanding paper and some quite coarse T-cutting compound.
If you enjoy doing this kind of work, it's deffo worth the money you have to spend on materials. They will last for a very long time. If this isn't exactly up your alley, I'd recommend leaving it to the bodyshop.
However, if you would like to know how this is done, I'd gladly demonstrate this on my silver 156 tomorrow and take a few photo's. I have a few stonechips that needs to be taken care of