Yes, the word plural is a noun.
No the word dancing is not a plural noun. When used as a noun the word dancing is uncountable.
No the word notes is a plural noun. The singular noun is note.
It is a plural noun.
No the word gazing is not a plural noun. The word gazing is not a noun at all but a verb. The singular noun form is gaze and the plural noun is gazes.
Yes, the noun 'mumps' is a plural, uncountable noun, a word for an infectious disease.
Yes the word warriors is a plural noun. The singular noun is warrior.
The plural form for the noun beneficiary is beneficiaries; the plural possessive form is beneficiaries'.
The word army is a singular noun; armies is the plural form.
The noun teeth is plural.The plural form is tooth.
The word confrontation is a noun. The plural noun is confrontations.
Yes, the word 'boys' is the plural of the noun 'boy'; the word 'boxes' is the plural of the noun 'box'.