RDD,
Great to be getting your nine year old intoduced to the sport, the earlier the better. I won't comment re the choice of starter gun brand or gauge as you have had plenty of comments and good suggestions already.
A couple of things hit me though on some of your other questions, and as parents all of us do this. It struck me that filing off "read owners manual before using" and "Stoeger" stamps, as well as the wood grain issue, is probably totally unimportant to her. My guess might be that starting out having her very own gun is the only thing that really matters to her, the fluff will come later to her as she grows in the shooting sports.
And while all projects of this sort for our kids are fun, that's a lot of effort spent on na Stoeger starting gun, sort of the equivalent of restoring a '57 buick when the same hours of time could have been spent on restoring a '57 Chevy or a '57 T-Bird.
Why not consider just doing the stock fitting work and leave the rest alone. Then when she is ready to move up you might be in a position to get her an ugrade gun that she will really appreciate then, and your Stoeger Starter is already set for the next child. You can also then spend your time improving the higher quality second gun.
Just my 1 cent immediate thoughts.
