It's a first date; don't presume you're getting some. You're not entitled to know intimate statuses until you're preparing to have sex.
If you get through a first date without finding out someone has kids, that kind of suggests they might be hiding those kids from you because your kids are a big part of your life and that just tends to come up. Finding out someone has kids after the fact is weird, but not necessarily a deal breaker.
Really, I don't think someone should feel forced to disclose any of this on the first date because there's plenty to talk about just focusing on yourselves. If they're expecting a second date though, yeah they might talk about the surrounding details.
Only if you're ugly you typically don't get laid on first dates. ---