I do a lot of interviewing.
I've always been told by HR that we are not allowed to ask if a potential employee is married. There is a risk of discrimination in the work world - someone who is married can be perceived to be potentially less available or less devoted. This can also be a source of discrimination toward women - obviously somewhat less of an issue here - when the hiring company can consider whether she is a risk to take maternity leave and increase insurance costs. So you are not allowed to ask that.
Yes, asking if "you like girls" is probably strictly illegal under workplace equal rights legislation. Not just NFL rules, and potential sanctions.
Anyone who asks that in an interview is an idiot. These teams should know this. You could potentially see other entities than the NFL raise eyebrows here.