Hypothetically, if you had a gas made of really heavy atoms/molecules (although it's unlikely that they would be stable at the kind of Uranium-heavy I'm thinking of, let's say that hypothetically they are) in a liquid made of really really light molecules or atoms (e.g hydrogen), and say that temperature isn't going to change the given states of the elements (very very hypothetically), and so they can exist in the states they need to together, could the bubbles go down? Or would the relative densities make the masses of the atoms and molecules irrelevant? 

A gecko sticks to a vertical surface because of the huge surface area on its feet (thanks to microscopic hairs). If you ran the gecko's feet under a tap, (or dipped it in a pond), would the gecko just slide down/fall off the vertical surface, because it's feet were busy sticking to water molecules instead?

And if it did, would it have the emotional capacity or facial muscles to look surprised? 

Melanin is a pigment found in the iris (eye), hair and skin. Melanin protects DNA from damages caused by the sun, hence the darkening of skin. However, hair tends to get lighter in the sun despite containing melanin....does the pigment have a different role here?