colon followed by a question

I did some search on the Internet but am unable to get clarity on this.

SET 1

Which of the following is correct?

A) Have you: Ever purchased a blue car? Ever visited Hong Kong? Ever gone on a long road trip?

B) Have you ever: purchased a blue car? visited Hong Kong? gone on a long road trip?

SET 2

I would also like to know if one needs to start a question after a colon with a capital

So if B is a better option, should I write ‘Have you ever: Purchased a blue car? Visited Hong Kong? Gone on a long road trip?

Here there is more than 1 question but what if there is only one question after the colon? Do I still start with capitals? If I substitute colon with emdash does the same rule apply?

Thanks