Answered Questions

Yes, capitalize the first word after a question mark or other punctuation, because it generally marks the beginning of the subtitle.

Technically the rule for article, chapter, book, and report titles is to "Capitalize only the first word of the title and of the subtitle, if any, and any proper nouns." p.185, sect. 6.29. There is no mention made of different kinds of punctuation marks. Students are often told to capitalize the first word after a colon because it's an easy way of identifying the start of a subtitle and the most common punctuation used before a subtitle, but the punctuation could also be a period, exclamation point, or question mark.