There's really two questions you have in there, and the answer is different for them.
Is it OK to ask multiple questions on a theme?
There's nothing in our scope or site rules that says your questions can't be similar to other questions. On this site, we also don't have anything in our rules that says they have to be notable questions. Idle curiosity and trivia has always been allowed. So, by that definition, it's "OK".
If the list of questions is short enough, and it's finite (its not getting any bigger), then asking one question may be better. But asking them separately isn't wrong, it's just not ideal. At some point you might trigger users to start downvoting your questions, especially if they start to sound too trivial or too insignificant. (e.g. asking for the favorite Quidditch team of some wizard we saw for a brief second at Hogsmeade.)
Which is important: the questions may be "OK" in the sense that it's acceptable to ask them, but that doesn't make them "good". And "not good" questions are liable to be downvoted heavily, which is one mechanism that might deter a user from asking too many of these over time.
What if a user decide to flood the site with these?
This, however, is bad, but for a completely different reason. Normally we "assume good faith" when users asks questions, no matter how trivial. Flooding the site question questions with the intent to cause problems, though, is clearly acting in bad faith, and is abusing the system.
A user that posts questions specifically to cause trouble or disrupt other user's use of the site is trolling, and they would be subject to action by the moderators. The kinds of questions is relevant only in that it would help a moderator make a judgement call towards the user's motivations. Floods of really high-quality, well-written, well-thought-out questions are unlikely to be done in bad faith (mostly because that's a lot of effort to go through), but floods of low-quality, boilerplate trivia questions might be. If a user were trolling the site this way, they'd be dealt with for that reason, not because their questions were bad on their own.