No it doesn't need to be hyphenated.
No, the word "middle class" is not hyphenated. It is used as a compound noun to refer to a socio-economic group between the upper and lower classes.
No it doesn't need to be hyphenated.
Yes, the term "fast-paced world" is hyphenated.
world-famous
No, "world leader" is not hyphenated. It is typically written as two separate words when used as a noun phrase. However, if used as a compound adjective before a noun, it can be hyphenated as "world-leader status."
Hyphenated words that start with the letter f:father-in-lawfine-tunefirst-class decisionforty-fivefour-fifths
The noun phrase 'four week vacation' does not need to be hyphenated.
yes for clarification
No, "reassigned" does not need to be hyphenated. The prefix "re-" is commonly used with verbs and is typically not hyphenated unless it precedes a proper noun or creates confusion. Therefore, "reassigned" is correctly written as one word.
No, "best in class" is not hyphenated. It is typically used as a phrase to describe something that is considered the best among its peers or category. Hyphenation is not necessary in this case because the phrase does not function as a single adjective modifying a noun.
No it doesn't.