It bonds to skin because
solid polymer requires the presence of water to get things started, be it in the air or on your skin. Without a little moisture, SuperGlue can't bond anything. This explains why the glue is so good at sticking fingers together.
I won't be able to give an exact number because we are not given with the volume of the diluent and the aliquot. In order to explain this, I can give examples.
Dilution factor is the ratio of the initial volume and the final volume. For example, if you add 0.1 mL aliquot of the stock solution to 50 mL of the diluent like water, the dilution factor is:
Dilution Factor = Vi/Vf = 0.1/(0.1+50) = 1/501
Consequently, the concentration of the sample is equal to the product of the concentration of the stock solution and the dilution factor:
Concentration of sample = 25 M * 1/501 = 0.05 M