Firmware upgrade question

Sorry if this is a silly question I am new to the world of mp3 players and  I wanted to know. If I have a Fuze bought in Canada and I put the Hebrew firmware on it -will it now make the menus etc all in Hebrew? Once I do this can I revert back to English if I wanted? I don’t wanna do this until I know what the consequences are… Is the firmware size specific? Does it matter if I have a 4GB or 8GB player or is firmware independent of the size?