You're ready for them whatever you're doing. Some days can be relaxing. Others it's one thing right after the next, and you might not get a chance to eat until late at night. You just don't know what is going to happen, which is part of what I like. Except for the three months during probation that I spent on a truck I've always been on an engine.
Engines carry water and hoses.
An engine crew's primary function at fires is to put the fire out and check for fire extension. Engines also respond to most aid calls. Going into a burning building is frightening and exciting at the same time. You don't have a whole lot of time to think about the dangers, really. Training takes over.