I see that you have a lot of questions.  I have one for you.  Who is the boss in your home?  If you allow your children to call the shots you are in for a long haul to try to turn the behavior around.  Allow me to make my point.  I was at the Dr's office yesterday and there was a young mother there with her little girl of about 14 months.  The little girl refused to leave.  The parent negotiated with the 14 month old who only could answer her mommy with a firm "no" otherwise all should could say were words made with grunting and gurgling noises.  Right away I could tell who was in charge!  The baby was able to convince her mother to come back to the waiting room, read a book to her while all the time the baby chatted and pointed at pictures on the wall, completely oblivious to the story itself.  It seemed that all she really wanted was control of her mother, and she had it.  When I was leaving my appointment, they were still there and the mother was still negotiating with the baby that it was time to go.  Don't let this be you.  I am a parent, what I says goes, and if you don't like it when you grow up you can do whatever you want. Good luck.