The series doesn't condone it, but we're under no allusions that House says these things because he knows it has power. Hard to say if he's sexist or merely knows how to manipulate - but it's definitely so close to the line, it's hard to call.

True. I remember a third season episode where Cuddy tells Wilson that she hasn't experienced House to insult just to insult (as opposed to insult because he wants to achieve something by it) with one exception, and when Wilson is disbelieving, she says that you can tell the difference because he really knows how to hurt if he wants to. (As the one exception was earlier in the episode when he told her she'd make a horrible mother, which she sees as a very different thing from their usual bickering and all his usual remarks about her cleavage, her dates etc., because it relates to something she has told him in confidence, the wish to have a child.) But even if we postulate that his usual brand of sexist remarks isn't genuine conviction but tool of manipulation - what difference does it make to the recipient, especially if the recipient, unlike Cuddy, doesen't know him? The CIA doctor being a case in point. As you say, it's hard to call.

Still, nine characters is a lot for any show - particularly one that is supposed to have a focus on one; that's a lot of extraneous characters to make fit each week.

It probably means that either someone else gets written out or they do what ensemble shows like, say, DS9 did, put a different focus on different characters each week. But as you say, "House" is a show with a clear lead who automatically has a larger percentage of screentime, as opposed to DS9.