Whether or not language is a folkway depends on how language is being used. A folkway is a behavior that does not have legal sanctions in society but is usually considered poor manners. Cursing may be an example of language as a folkway.

A common reward for a folkway is social acceptance. A folkway is the normal behavior people follow because of tradition or convenience.

Yes. Yes it is.

A folkway is a social idea shared by most people; they are also called morals. The reward for following folkways is social acceptance.

Social acceptance