First off a little background from you would help; what state are you in? Do you have any certifications such as codes enforcement, fire inspector I or II, or any others pertinent to the job?
I am technically a Fire Inspector I for my state of NY and work to inspect homes where developmentaly disabled live, and review the inspection and testing records for alarm and sprinkler systems, and investigate the cause of fires in the homes along side state fire and local fire chiefs.
My interview was not any different from other jobs; questions about my experience, especially codes enforcement, issues I have found in the field and how I mitigated them, some basic knowledge of codes and inspection procedures, what I feel my strenghts and weeknesses are and where I feel I can improve, questions about my firefighting experience and some other basic interview questions.
Just remember the "greatest achievement", "whats your biggest accomplishment while at work", and the "you see a fellow employee cutting corners on an important project or breaking the policies, what do you do?" questions and think long and hard about some decent responses you can use. Almost all professional interviews have questions like that.
Good luck with the interview, and dont have that mindset of "im a small town guy" when you go, think positive, dont be too confident or cocky, be polite, crack a joke to break the ice but then act professional, shake hands firmly with eye contact, look into their eyes when speaking to them and dont fidget or have any other nervous activity like wiggling feet, bighting lips or sighing. Good luck, feel free to send me a PM with your email and we can chat more if you like.