OK, just in case you try to look something up on this plane, it's made by Sterling Models not Stirling.

In your first set of pics you said you had the missing flaps. OK, those are ailerons.

In the last set of pics you said you have holes for "extra" flaps. OK, those are the ONLY flaps.

Also in the area where you sanded it appears that fiberglass weave can be seen so at least this portion is fiberglass covered. The "gloss" is from whatever was used to apply the fiberglass.