Although you do want to ask some questions at a job interview to show you are interested, there are certain ones that are better left until later in the hiring process. Asking the wrong questions at the wrong time can make you look pushy or even unprofessional.
For example, a first interview may not the best time to bring up salary. Standard interview etiquette dictates that you should either wait until the interviewer brings this subject up, or at the very least wait until toward the end of an interview. Many people pass on this topic altogether until a second meeting or later discussion. Benefits are another subject that is better left alone at a first interview. Although you may well be concerned about this topic, be patient and focus on getting the job before you worry about what you will be getting from the company.
One thing you can do is get an idea of what jobs in your career field are paying these days. Whether you are interviewing for freelance copy editor jobs or something part time, there is value in knowing a bit about what the going pay rate is. The same is true if you are looking at signing on to a more permanent position. If you do some advanced research you'll be current and ready to talk intelligently about pay and benefits when the time comes.