Are Mr. Mrs. Ms. and Miss suffixes?

No. They are "honorifics" or "courtesy titles." They are used in front of a full proper name (Mr. Smith, Mr. John Smith) in the same manner as Dr., Rev., Gov.,or other titles.

Mr. (capitalized, with period) is "Mister."

Mrs. (capitalized, with period) stands for "Mistress" (married woman).

Miss (capitalized) is an unmarried woman.

Ms. (capitalized, with period) is a woman of unspecified marital status. Its use grew from the feminist movement and does not have universal acceptance. But it does allow a feminine form of address where no status is known.