Question about the proper word choice
There's a nuanced difference between That's all and, say, That's all I had. The latter can have a tinge of deference and the former can have a tinge of command, as if you were running the interview.
But a deferential tone of voice and body language would probably counter the latter effect, and even if it didn't, some interviewers would appreciate the fact that it's a two-way meeting, where the candidate wants to learn about the organization just as much as the organization wants to learn about the candidate.