No.
No, "miles per hour" is not hyphenated. It is written as three separate words.
It should be hyphenated.
No it shouldn't be hyphenated. It is one word.
Hyphenated
It depends. If you are saying "The store is open 24 hours." then NO. But if you are saying "It is a 24-hour store." then YES you can. It is often hyphenated when used as an adjective preceding a noun. There is no definitive rule, but it is quite common to hyphenate 24-hour in these cases.
Yes, one-on-one is hyphenated. I don't know why, exactly. It just is.
Yes, end-product is hyphenated. It is a noun and treated as one word which is hyphenated.
in-house - two words, hyphenated.
What about the adjective form? e.g.: We went on an hour-and-a-half long drive.
It is a hyphenated adjective, life-giving.
It should be hyphenated.