Are there instances of papers the first parts of whose colon-wise titles are questions?
There are plenty of articles that have a title in the format &quot;Question? Answer/Suggestion&quot;, however, without colon.
I'm pretty sure that you cannot have a colon following a question mark, given a question mark indicates the end of a sentence (same as full stop and exclamation mark).
See also this question on english.se: https://english.stackexchange.com/questions/51485/sentences-ending-with-both-a-colon-and-a-question-mark