Iphone 3 sim to Samsung Galaxy Note?

I currently have an iPhone 3 (yes very old) on an optus plan- its time i invested in a new phone! I'm interested in the Galaxy Note, it looks awesome. However, i plan on moving to Europe next year so it wouldnt be wise for me to enter into another contract with Optus. So i was thinking of buying the Note online and then entering into a sim contract with Optus where you BYO phone. My question is weather the Note should be unlocked so i can take it overseas? And also, am i able to directly put my current sim into the Note with a new BYO contract? THANK YOU!