There are two career paths in the FDH at present:
Fire and Rescue
EMS

Here i'll list the ranks within the fire and rescue side of the department and how to go about promotions, EMS will be up soon.

Fire and Rescue:

Probie - Probationary firefighters are the new guys, fresh out of the academy and itching to learn. Probie's are monitored closely and guided by higher ranking firefighters. They'll need to be trained in using an SCBA set (self contained breathing apparatus) and how to work effectively as a firefighting team. ((Usually they stay on probationary status for around a year, but for the benefit of the Den and RP it will just be a month, maybe a little more.))

Firefighter - No more bullying, abuse and hard labour from your superiours, your one of the team and fully qualified to respond to car crashes, fires, rope rescues and much more. Your basic firefighter, loves to bully the probies and give them a hard time.
To progress to the next rank of Lieutenant, you must take an exam ((which has been made)) to assess your leading abilities and overall firefighting knowledge. You will need to have a reasonable amount of experience before being elligible to take this, however.

Lieutenant - Company manager and the leading firefighter. The Lieutenant ensures that the firefighting team acts and works efficiently and gets the job done. He'll be leading the firefighting team on call-outs and will usually be in charge unless the Captain or Chief is around. To move up to Captain another exam must be taken to assess the firefighters leading abilities and situational awareness.

Captain - Company and station manager. In small stations such as the firehouse in Hathian, it's common that the Lieutenant and Captain will work different shifts so there will always be a commanding fire officer at one time. Captains will usually be in charge of a situation, and if a lieutenant is present, the Captain will instruct the Lieutenant and his team on what to do.

Fire Chief - The fire chief is responsible for the operational and administrative efficieny of the FDH. For small incidents it is rare that a chief will respond unless the firefighting team is low on numbers (( which for now, will probably happen a lot)). The Fire Chief will take command of large scale rescue operations and major incidents ((high rise fires, chemicals leaks, etc etc))

The Fire Department is always recruiting full-time or volunteer firefighters so feel free to drop by the firehouse anytime.