Is such a common noun

Answer 1

No, the word 'such' is not a noun.
The word 'such' is an adjective, an adverb, and a pronoun.

The adjective 'such' is a word used to describe a noun as of a kind specified or indicated; as so remarkable.
Example: We're not used to such weather this early in the year.

The adverb 'such' modifies a verb, an adjective, or another adverb as to such a degree; to an extreme degree.
Example: We're not used to such nice weather this early in the year.

The pronoun 'such' is an indefinite pronoun, a word that takes the place of a noun of a type previously mentioned; someone or something stated or implied.
Example: This time of year, we usually have snow, sleet, and such.