IMO Casey is NOT intelligent. Big difference between being (somewhat) articulate and intelligent, and we all know that she LOVES to talk. From what I've observed she also has a limited vocabulary as well..using the word "absolutely" over and over. Becomes annoying after awhile.
I agree with you, sadly the site where she dumped poor Caylee was a convenient place for her. I also think that when Caylee was found, she thought she would never be considered as a "suspect", as she would be able to lie her way out the kidnapping and murder charges with her "nanny" story.
I think that she also told JB where the body was, and also her family was told, and the PI went out to the site prior to Caylee being found in order to move the remains so that the police would never find her. Also, as a defense strategy, her family was continuing to act as if Caylee was still alive prior to her remains being found. That's my opinion though. In KC's narcissistic mind, I think that she thinks that JB is going to get her out of this "mess that she's been wrongly accused of" somehow, and she has told him "everything" (however I seriously question her veracity of the story that she has told him). JMO