The term "high five" does not require a hyphen when used as a noun or verb, as in "give a high five" or "they high-fived." However, it can sometimes appear hyphenated ("high-five") when used as a compound adjective, for example, "a high-five gesture." In general usage, the unhyphenated form is more common.
It does not need to have a hyphen! :)
yes
No, the word "nineteen" does not need a hyphen when written numerically.
No
I do not believe that multitasking is supposed to have a hyphen.
It's not a word in the dictionary, so yes, use the hyphen.
You typically need only capitalize after sentence-ending punctuation, which a hyphen is not.
no
No.
no
No
Yes, in-home does need a hyphen. It's two words put together to form a word for a different concept.