What are exchanges like "How are you," "I'm fine," and "See you later" called?

This is an example of phatic communication:

phatic [ˈfætɪk] adj (Linguistics) (of speech, esp of conversational phrases) used to establish social contact and to express sociability rather than specific meaning

They are called pleasantries. From The Free Dictionary:

pleas·ant·ry (n.)
1. A humorous remark or act; a jest.
2. A polite social utterance; a civility.
3. A good-humored or playful manner in conversation or social relations.

It just occurred to me that "formalities" is what I was looking for.

Depending on the extent of the conversation "small talk" might be applicable too. This would cover not just the formalities (which are specifically things that are necessary, not just chit-chat) but the ensuing social niceties, banter that helps to fill what would otherwise be potentially awkward silence or whatever business was to be conducted.

That's about five answers right there.