Available fresh or dried. Fresh can be used to enhance salads, dried can be used to enhance sauces, sautes, and roasts. A good herb to move on to if you ever get sick of oregano. A pleasant, distinctive flavored herb, available fresh or dried. More functional than sage.
White pepper is simply a black peppercorn without the black exterior case.
Some people use white pepper when making cream sauces that they would prefer to keep all white. I say integrate your sauce, and leave the white pepper on the shelf at the store.