No it doesn't require to be hyphenated.
Yes
No.
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.
No, a hyphen is not needed.
The correct spelling of hyphen is nephyh
Tumblr URLs can't start or end with a hyphen.
No, faux pas doesn't require a hyphen.
No.
Yes
It is preferable to hyphenate that word whether it is used as an adjective or a noun, but yearend -- one word -- is also acceptable. I always wait for the year-end sales to buy new furniture. I can't file my taxes yet because I am still waiting for my year-end documents.
Ideally, yes
These are two words. There is no hyphen in the concept. In charge means to have leadership in English, so there is no hyphen to connect the two.