Yes, "year to date" should be hyphenated when used as a compound adjective before a noun, as in "year-to-date performance." However, when it appears after the noun, such as "the performance year to date," no hyphens are needed. Always consider the context to determine the correct usage.
Hyphens not needed
Yes it should.
no hyphens - 57 years old is what you are.
Yes it should be hyphenated.
If you're using the phrase as an adjective (example "This easy-to-use remote is great!") then it will definitely need the hyphens. Otherwise, the hyphens are incorrect.
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.
It should be "up-to-date". You will see it in many instances written "up to date" without the hyphens, where each word becomes a separate and different part of speech, which may be confusing. (Hyphens are grossly and woefully under-used in adjectives.)
Most people would spell it sixteen-year-old child. But over the last 20 years, people are ignoring the hyphens.
Yes, "year after year" should be hyphenated when used as a compound adjective before a noun (e.g., year-after-year performance). However, it is not hyphenated when used as an adverbial phrase (e.g., they met year after year).
No, you should not.
Yes, when used as an adjective. Year-to-year is hyphenated when used as an adjective: year-to-year comparison, year-to-year budget. Year to year is not hyphenated when it is used as a time period: We come back to this same beach year to year.
Both of them should be.