Yes
No it doesn't require to be hyphenated.
Yes it should be hyphenated.
Four-year should be hyphenated but not institution.
It Is A Special Hyphen
Non-breaking hyphen
Nonbreaking Hyphen
If you're using the phrase as an adjective (example "I hate the end-of-the-year audit!") then it will definitely need the hyphens. Otherwise, the hyphens are incorrect.
You should use a hyphen to represent years with more than two digits that end in a number other than zero, such as twenty-seven and one hundred and thirty-three. The hyphen is only used between the last two digits.
No, a hyphen is not needed.
No, the sentence should use a hyphen to connect "dead end" as a compound modifier: "He knew he had a dead-end job the first day he showed up for work."
Tumblr URLs can't start or end with a hyphen.