Given your child's age, her wishes may be taken into consideration and you would be awarded more parenting time, so it would no longer be 50/50. But joint legal isn't going to change.
Since the uncle is a convicted sex offender, you can get it in the court order that the he cannot be around your child. At all. Especially since his victim was a minor child. Doesn't matter if he's eyes on by another adult. He's a danger to the child.
Secondhand smoke, since you didn't have a problem with it when the parenting time was first established, there's not much you are going to be able to do it now.