The answer is no, yes, and maybe.
Under the terms of the Civil Rights Act of 1964, employers are forbidden from considering race, gender, religion, or national origin in regards to their employees. Attempts are being made to broaden the application of these laws to include sexual orientation as well.
The coverages of these laws are usually described as prohibiting "discrimination", i.e. a differential treatment based on prejudice related to the aforementioned categories. This typically assumes discrimination against groups that, in common perception, are most frequently discriminated against, such as women. However, it does not explicitly detail the implications of "positive" discrimination, such as hiring a woman because she is attractive, or hiring a person based on their ethnicity in order to appeal to that ethnic group. Moreover, under affirmative action, employers are actively encouraged (and in some cases, mandated) to hire or promote certain ethnic or sexual groups in order to maintain a certain quota of representation. For example, some fire and police departments are required to hire employees that in proportions that equal the racial makeup of the city they serve (Penn/Stump v City of Oakland, 1967). Howeover, quotas are illegal, and so these targets are instead described as "goals".
Thus, these laws may seem contradictory; an employer may not consider race or gender when hiring, if that might result in NOT employing the candidate, but the employer may, and may even be required, to consider race and gender in order to actually hire or promote the candidate. These contradictions are the source of much criticism of equal opportunity and affirmative action policy.
Yes. Some people have to be fit for the right thing, such as advertising a women's store..you wouldn't want to have a guy wearing a dress and high heels.