I meant to respond to this days ago, but spaced it out.
For sanding down the sprue nubs I use a diamond imbedded metal nail file. Mine is about three inches long (by Revlon, I think) and they also make a longer one. It costs about three bucks at the drugstore, or the cosmetics area of Walmart or Target.
I use the metal file to flatten the mating surfaces of wings, too. Being made of metal it has very little flex, so I can hold it across the chord of a wing and can sand both edges at the same time, ensuring that the gluing surfaces are totally flat. It leaves a rougher suface that gives a perfect "bite" for the glue to interact with.
Also, thanks to my girlfriend, I discovered finger nail polishing sticks, as mentioned earlier in this thread. One side has two different grits and the other side is for final polishing. Like a one, two, three, step process. I've used it to polish out paint blemishes and it works great, but be sure to use water with it, like wet sanding, as the paint will build up on the fine grit stick. They cost less than a buck apiece.
These two tools are pretty much all I need to use to clean up parts before gluing them together.
Hope this helps.
stinger