Do I pay duty to import goods that I plan to sell on outside the EU?

Question

I am going to buy goods (import) from America and sell (export) goods straight to out side EU. Do i need to pay import duty?

If yes, can i claim it back and how?

If no, do i need to fill in any form? or just notify the courier about that?

I would like to say thank you very much to the persons who reply to my question. I really appreciate it.