I am just about finished with my GHK Serum Sample and would like to start the CP Serum I purchased. Since it seems eye makeup is the culprit in much skin damage -- would it be ok to use a teensy drop of CP Serum on the eyelid prior to applying powder eye shadows, liner, mascara etc?

Yes, use a very light coating of CP Serum before the color cosmetics. This will act as protective barrier for the eye area skin.