Re: Legitimate
Constant:
So, is my preference for a female secretary (assuming I have one) sexist,
Probably, but as I said, I don’t know. What’s the reason for your preference? I can imagine sexist, anti-sexist, and sexism-neutral reasons for preferring hiring a woman (as such) rather than a man. Without knowing which one is hypothetically yours, I can’t answer the question.
and if it is, is that immoral?
Yes, if it is, it is (therefore) immoral.
Constant:
Is it sexist for a man to lust after women?
Depends on what you mean, I guess. If you’re asking whether it’s sexist when the particular people you’re sexually attracted to all turn out to be women, then no, I’m not claiming that. If you’re asking whether it’s sexist to lust, more or less indiscriminately, after “women,” due to some kind of attitude towards femininity in general, then that may well be sexist. In any case it’s immoderate and objectifying.
More to the point, while being male and heterosexual is not, as such, sexist, there are a lot of things commonly associated with heterosexual male “lust” for women, as it is actually felt and expressed in the society we live in, that are sexist. For example, preferring to surround yourself with women in subordinate positions to you so that you can ogle them or sexually harass them is fairly sexist, and, as I said, fairly sleazy.
If one’s preference for associating with women rather than with men in a particular context is based on different reasons, then who knows? It may well be neither sexist nor sleazy.