So temperature is only transferable kinetic energy of molecules.
I don't think this is right. Temperature is a measure of an atom's vibrational energy. Heat is the transfer of thermal energy, temperature is just how much the atom is jiggling. Absolute zero is impossible, and since the universe seems to be quantum, it's probable that every atom can only reach a certain lower temperature. Let's say that value is 0.1 kelvin for hydrogen. That 0.1 degrees kelvin is non-transferable, as the atom cannot lose any more thermal energy.

What happens when water gets to 100 degrees is that it starts to boil, and this phase change takes energy. That is, it literally cools the water. This is why sweat has a cooling effect, because it evaporates and takes heat with it. So the added heat you are putting into the water is replacing the heat that the evaporation is taking out.

I still don't understand enthalpy, so I'm not sure how this fits into the picture. Entropy increases though because heat is being lost to the atmosphere. If literally all the heat you apply to the water is absorbed by the water, then perhaps during boiling entropy is constant, idk. But this is impossible, you're always going to lose heat to the surroundings. You'll never have a perfect vacuum, there is the object that applies the heat, there will always be loss.