Questions to ask in interview

I’ve heard that employers hate job seekers who say ‘No’ when they are asking for questions. It makes them assume that the job seeker is not interested in getting the job. What should I ask on an interview without being appear to be asking for too much? Should I ask about salary and off days? I don’t want them to think that I am all there for big money or relaxing job however I am afraid to get offers that I don’t deserve.