"The single thing I find most infuriating about the Golarion setting, and, honestly, my only real complaint, is the inconsistency of their goddesses and gods. I understand that the gods have some sort of pact mumbo-jumbo keeping them from interfering with mortals . . . except not really, because they still interfere with mortals. They still send prophetic dreams and perform miracles and save adventurers who are in dire straits, but only once a campaign. So . . . are they allowed to interfere, or not?"
Yes they are allowed but so are other gods and deities. Incident with Rovagug is one major example and incident of Desna killing a Demonlord is one minor example on why direct interference is bad idea. Gods risk messing up the material plane or death.
"No benevolent god could allow such things as lycanthropy or malaria or Rovagug cults to exist and hurt people. Any god that sits on their ass and watches mortals suffer and die without lifting a finger to help is clearly not a benevolent deity."
That is why they send their mortal followers and sometimes their heralds to deal with the problems. Direct interference is just going to piss of other deities.
This question was posed to me the other day, and while my default assumption is 'no, probably not', there are a lot of good deities and there could be one that's particularly pragmatic about it, even if they would never condone it.
All of them tolerate, since Necromancy is not evil, only some spells are evil.
Good deities oppose spells with [evil] description.
"The character tortures, kills, and eats peasants/slaves, preferably children, anything that she can legally get away with."
Cheliax laws are not really known, but since society is lawful, I believe that anything that disrupts public order (going around killing, eating and torturing people) and "property laws" (harming slaves that you do not own) are going to land huge problems for you.