Questions about your plans to have children, race, sexual orientation etc would all be illegal - basically anything that it is not a relevant question to figure out if someone would be good at doing the job or not.
religion?
Cuz
If you are asked an illegal interview question, the best response it to politely not answer the question and to ask the interviewer the intent behind the question. You can also go ahead and answer the question, or you can flat out refuse to provide an answer.
Do you mean what kind of question you might be asked, or what kind are legal/illegal for the interviewer to ask? Requirements can vary by state, though Federal law supercedes.
Probably Yes if in the US, Canada or EU - in the EU it is illegal to ask such questions in an interview or afterwards. Depends on the question whether or no it is sexual harassment. Most companies have a personnel dept; if not, in the UK go to the Citizens Advice Bureau
Does the illegal alien have to interview in her country for her F-1 visa
emergency
yes
Yes, it is illegal to fake a degree as it constitutes fraud and can result in legal consequences.
Yes, it is illegal to fake a diploma as it constitutes fraud and can result in legal consequences.
The applicants technically are not ignoring illegal questions, They are oblivious that the questions may be illegal.
If it can it does, however it will not do anything illegal and it relies on "the world" to answer the questions you ask - there are no staff answering questions just other people.