Someone else may have touched on this already (the subject here intrigues me, but I did not read through all of the pages, so if I am repeating someone else's thoughts, forgive me please).
For me, there is no strange mystery to this phenom with KC dropping Caylee off at her mother's or where she was going when CA and GA thought they were with "the nanny".
From what has been released so far, here is how it seems to have played out.
To avoid conflict at home, KC says she is working late and that Caylee is at the nanny's.
Meanwhile, it's really KC taking Caylee to Ricardo's to spend the night.
CA thought KC was working and Caylee was with the nanny, but KC and Caylee were together with Ricardo, or Jesse, or wherever they were - but they were together.
The times KC dropped Caylee off at her mom's work to "go to work" - no work, no job - just hanging out with various friends, probably at their homes, or apartments, until the clubs opened. (Remember, KC had lots of friends and acquaintances.) Also remember that one of KC's fake work emails told her to bring extra clothes (jeans, etc).
As far as money, and where did KC get the money, remember she had been stealing from her parents for years - so much so that there were major financial difficulties in that house. LA also stated that KC stole from him and his friends.
IMO, KC invented Nanny partly to explain why she had no money leftover from "job".
KC is simply a selfish, irresponsible monster who wanted to do what she wanted when she wanted.
No prostitute job, no mystery, simply a selfish monster who, when she began dating AL, realized that Caylee was no longer welcome for overnight visits, and since she was so selfish, decided that Caylee had to go.
Afterall, CA was no longer willing to watch the child 24/7 and KC had no where else to turn (no money for a real sitter, no desire to have CA get custody of the child, and no resources other than her own warped brain).
IMO, KC was treading very thin ice, for a long time. And AL, through no fault of his own, was the clincher. He did not want Caylee around, and KC for whatever reason, felt that AL was her knight in shining armor.
ADDED: I wish there were another, more mysterious story that would explain why KC felt she had to do this, or why this happened, but I am 100% FIRM that this child's death was not accidental, nor did a "prostitute" or some bad character commit this crime. It's so hard for me, and others, to actually understand that this 22 year old woman INTENTIONALLY MURDERED an innocent, beautiful child. But sadly, this is exactly what it appears to be.