[nano]

Hi guys, I am leaving on vacation for 1 month to Hong Kong, ive never really left the country with a phone before so I am not sure what I should do....If I take my phone with me, can I still keep it on over there without getting any long distance roaming charges if i dont pick up/or make any calls?...for example i leave it on and someone from canada calls me, i can see whos calling but if i dont pick up i dont get charged right?...also regarding data, should i turn it off or leave it on as long as i dont use it i wont be charged for it?....because i know imessage and whatsapp is done through data/wifi so i dont know how much a txt msg would cost through those, i honestly dont mind paying some money for being able to txt people through one of those avenues for the month I am there...anyone have any advice? thanks! I have a iphone 4 if that matters