Morph unisex-child Piggy Back

What size is this? My son is 10 yrs old so I would need the biggest size

I am 147 cm will I fit with the large size?

what size child would this fit? I see it is one size fits all but will it fit a 4' 7" thin girl?

Does the alien include the area 51 outfit hes wearing? I ordered this costume feom walmart but the aliem doesnt have the area 51 costume on.