PT What was Dooku told the plan was when he “captured” Palpatine?

Hmm, I like the mask idea. If that is the case, then they don't have to worry about the separatists's interests at all; they just need to focus on establishing the empire. They must have intended for Palpatine to escape at some point, either through Anakin and Obi Wan's rescue or shortly later by some other means.
A possible supposed purpose of the kidnapping then might be a sort of "wake up call" to get the public to know how intense the war is. We do see that soon after Palpatine's return, the senate votes even more executive powers for him (in fact, my mom actually thinks this was the real reason for the kidnapping).
In addition, Dooku might also think that it is his mission to eliminate the prophesied Chosen One. Sidious might have hyped him up for this battle by repetitively mentioning to him how Anakin is improving quickly and becoming more and more of a threat, and how they have to get rid of him before it is too late.

Yeah good point, the Jedi might expect Anakin to die fighting.

 

No, he can't. But he can say that he considers Skywalker a great asset for their purposes and wants him turned. Wether Dooku agrees that he would be a great asset or not, why would he dare to ignore direct orders from his master? I don't see Sidious making a move like this if he didn't thought Anakin was capable of facing Dooku. And if for some reason Anakin wouldn't be turned, and Dooku got the upper hand and defeated him, then he would have proven himself worthy of remaining his apprentice. Sidious wins either way.