Generally the DNA molecule is double stranded to RNA's single strand. The RNA molecule uses uracil as a base while the DNA molecule uses thymine. RNA has catabolic properties that allow it to act in things such a ribosomes and tRNA. DNA is just a carrier of the genetic information.
Movement of molecules of a substance from its higher concentration towards its lower concentration by their own kinetic energy is called diffusion.
This is very common, although I dont think that the color of your hair is a recessive trait, for instance if you have two parent s that are both a brunette, like mine, you could still end up look me with blonde hair. It is a recessive trait to have strait or curly hair though.
Fertilization occurs when a sperm cell and an ovum fuse, resulting in a fertilized egg.