(1)Anakin was not that instrumental for Palpatine's plans. Palps could monitor his character closely, and had realized that Anakin is not going to be easily corruptible, he could have just not discard Dooku, and not reveal himself openly to anyone until Order 66. Maybe Sidious does have an impulse to find a successor superior to himself, but most of his actions point to the desire for UNLIMITED POWERRR!!! being stronger, so he's fine with training Maul wrong as a joke, using Dooku only as an ultimately expendable pawn, and stick with crippled Vader.
(2)Yeah, sure, boning a cocky, self-centered teenager with such vastly inflated opinion of her intelligence and capabilities that she is literally the best person to frame for something one could ever find (and boning whom is not just the matter of wanting to have your cake and eat it too, but actually morally dubious, besides probably being legally indefensible), would totally not give Palps alternative hooks to put into Anakin.