Can I work as translator with the army?

The 09L program for Arabic speakers has been suspended, so you cannot join as a translator at this time. You can still join the Army if you want a different job since you have a Green Card but you cannot get a job that requires a security clearance without citizenship. Once you leave for basic, you can apply for citizenship free of charge one year after joining or one day after arriving in a combat zone, whichever one comes first.