Flash T999 to other international stock Firmware

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http://forum.xda-developers.com – Hello everybody! i got my new Galaxy S3 finally from USA Tmobile, the phone is unlocked and it's version is sgh-T999. i want to flash it to other International European versions, will it be a problem? or i need only stay with what t-mobile 4.04 supplied me? Is is9300 same as sgh-T999?? Another question, if i cant flash it to international stock firmware, how can i delete all the other T-mobile stuff that came with it? will it be deleted with normal factory reset? Also can i install any other kernel on it? Im sorry for the many questions, i had before galasy S1 and i was used to fl (HowTos)