yes
It should be hyphenated.
Yes and no. The out-of-plumb wall should be hyphenated while the wall was out of plumb should not.
No, the phrase "thank you note" is typically not hyphenated when used in a sentence.
Yes, one-on-one is hyphenated. I don't know why, exactly. It just is.
The second word should not be capitalized
No, the phrase "hour and a half" is not hyphenated when used in a sentence. It should be written as three separate words. However, when used as an adjective before a noun, it can be hyphenated, like in "an hour-and-a-half meeting."
I really doesn't matter, but if you're writing an essay or something, keep all words that can have hyphens, either wil hyphens or without them. My point is that you want to be consistent.
Yes, "half-page ad" should be hyphenated to show that "half" and "page" are acting together as a compound adjective to describe "ad."
Yes, it should be hyphenated.
Yes it should be hyphenated.
Yes it should be hyphenated.
yes check-up should be hyphenated