DisguiseAdult Disney the Little Mermaid Ursula Inflatable Adult Costume | Women's Ursula Cosplay Outfit Costume (pack of 1)

I am a consistent size 2 or xs. I really want to order this and surprise my granddaughter but torn between small and medium. Any suggestions?

Is the necklace included?

Does the wig come with it?

I cant find the instructions to blow up the legs, does anyone have any they can post please?