Yes Jack is full skeleton. He hasn't noticed yet because he was wearing gloves and a full suit. 

Figuring Elizabeth was 11 when Jack died to have a kid who is younger, I was thinking around 10, she would have to have had a kid at 59. Which I guess is possible. It's not really ideal, but I know people that have had kids at that age.

Or maybe she's Elizabeth's granddaughter... making her Jack's grand niece