I know I’m a bit late replying to this and perhaps you know the answers. To become a firefighter in Spain you need to pass the ‘oposicion’ - open selectivity tests. Naturally you’ll need to be fluent 100% in castellano, then the tests are theoretical, practical and physical. Depending on where you are applying the pass marks and the tests will be slightly different. There is a big market in schools helping to prepare you for the tests, they are not cheap but they are rigourous. They also have lists of all the job vacancies nationwide. There is a lot of competition for these vacancies with some very well prepared candidates. If you are in Spain already, buy a local Spanish newspaper and you’ll see the small ads for the schools - ‘Hazte Bombero’ . In my business I see people preparing these tests daily. If you meet the language requirement, you may have a chance.