VICHYIE womens Tank Tops Casual

If ordering based on size chart, i’m xl but i’m a m in us. please clarify why it says to order smaller? is the chart accurate?

I'm 5.3”,100lbs but a 32DD,what size should I get in the white?

The pink color does not come on here, is it hot pink?

Where do you measure for bust (under or across largest part)?