You shouldn't be worrying too much in advance : the company that will hire you will make sure you learn everything you need to do the job.
I have no clue how they work at BRS, but there are two types of dispatchers out there. Those who only take care of all the activities around the aircraft, as there is a Centralized Load-Control, and the others, who also do the load-control at the aircraft. The biggest difference is that while you coordinate all the teams around the aircraft, if you have to take care of the load-control aspect, you must take care of the time even more, in order to keep a few minutes for you to prepare and issue all the documents.
For the rest, the most important thing is to be able to monitor timings and make sure to optimize the time available in order to avoid delays. The ability to resist stress, particularly when something happens that will delay the flight, but is out of your control (usually pax related...). **** happens, all the time.
Good luck anyway, hope you'll have the chance to do the job you want! You'll see, it's a real fun job, every work day, every flight is different. And, if your day didn't go well? Tomorrow is another day, with other flights, whatever happened yesterday
That's what I miss the most, actually.