No. A conundrum is a riddle or puzzle, especially a complex one. A more specific use of the word is "a riddle that is answered by a pun."The term "malaprop" or "malapropism" is applied to words that are used out of context because they sound like other words (e.g. a sneak in the grass).
No, but sometimes "average" means "mean" - when it doesn't mean median, geometric mean, or something else entirely.
The answer will depend on who you mean by HE.The answer will depend on who you mean by HE.The answer will depend on who you mean by HE.The answer will depend on who you mean by HE.
See mean-8. Or get a dictionary.
There is no statistical term such as "deviation mean".