1)
If Yo'av told her what to say, why did he need a Chachmamah?
1.
Radak #1: So she will know how to answer with Chachmah to what the king will say to her. Yo'av did not know everything that David will say; he told her only the basic theme.
2.
Radak #2: Yo'av told her only the action (he wants to reconcile David with Avshalom), and she thought up the parable.
3.
Malbim explains that Yo'av anticipated everything that David will say, and told her all the responses. Perhaps he holds that he needed to a Chachmah to be able to feign mourning. (PF)
