Living in amsterdam, studying in Rotterdam. Is it possible ?

when i say studying i mean taking the train once a week!
Im considering taking a course in the SAE institute of Rotterdam, (its not available in SAE Amsterdam), i would have to go just once a week.

My girlfriend is going to be living in amsterdam at the time, so i would love to stay with her.

I heard i can buy an OV chipkaart with a 40% discount for 60euros. I also heard that i can get a really good student transportation discount also.

P.S.
How easy is it to find a job?... like any kind of job, i wouldn't mind being a bartender, desk clerk, cafeteria attendant, waiter, food preparation asistant .. or something like that. maybe a call center phone operator also


Important data:
-I have a dutch nationality (but im essentially Costarican)
-I only speak English and Spanish (yeah, no dutch)
-it would be from 3 to 6 months