Yes you should always use a period.
We put the period after the word Mr because it's an abbreviation for Mister.
No, "Mr" does not require a period after it. It is considered an abbreviation, and in formal writing, the period is typically omitted.
Yes, the general rule is that where a word is abbreviated it is followed by a full stop to indicate this. For instance Mr. is an abbreviation of Mister.
No, but you need to capitalize it. You put a period after Mr. because it is short for Mister. You put a period after Mrs. because it is short for Missus. But Miss is already a short word so doesn't need an abbreviation.
Yes you should always do that
No, the abbreviation "Mrs" does not require a period.
Mr. is the abbreviation for the proper noun Mister, a title. Proper nouns are always capitalized, as well as the abbreviation for a proper noun.
Yes, before the name. So, it should be written as "Mr. Smith".
You put a period after all of those in the states, however, the British system requires no period after such abbreviations, Mr Mrs Ms .
Yes, Mrs. has a period because it is an abbreviation and mrs is not a word. The same holds true for Mr., Dr., and Ms.
Most people in the US do. It seems to be rather hit or miss in the UK (same with the abbreviation for "mister", which is usually Mr. in the US and seems to often be just Mr in the UK).
Traditionally, a full stop (also known as a period in the US) follows an abbreviation. However, where UK English is employed, such as the UK, Australia and New Zealand, placing any punctuation after an abbreviation is outmoded, and no longer required. For example, a word such as Dr or Mr has no full stop after it in Australia, but in the US it is still written as Dr. or Mr.