Sperry Top-Sider Women's A/O 2-Eye Leather Boat Shoe

What size can I order if in most shoes my number is 38 - 38 1/2 European, in adidas I am 7us?

Are they originals or fake?

What is the order number of sperry womens 2eye bionic boat shoe - shoebacca?

Why are the sizes for the shoes so confusing ? Can you please explain what each size means