I've been to a Coast Guard Unit with firefighters. They had some full time paid staff and a few volunteers. Most of them appeared to be called Engineers. There were a couple of station Captain. Their Fire Chief was a very jolly guy!
You start off as a Fireman Recruit. Then it's a Fireman Apprentice After this it's a Fireman. I am basing this on enlisted rank insignia that I have seen on the coast guard. I have no idea what these ranks mean!