#3 is certainly wrong. The difference between passé simple and passé composé is not at all the same as the difference between simple past and present perfect. Passé simple and passé composé are pretty much interchangeable with regards to meaning. You can take any sentence and switch between the two, it will mean (almost) the same thing (with some differences in subtext, passé simple is for more distant past). This isn’t the case for simple past vs present perfect, often you can’t even do this switch and keep a meaningful sentence.

Passé simple is simply the tense used for literature, even if orally nobody uses it anymore. “Even” for detective novels (although I’m not sure why detective novels would be “less formal”), passé simple is the tense of choice. It has nothing to do with the age of the novel.

However, even for literature, passé simple is starting to decline somewhat. Book meant for children/teenagers are starting to be written in passé composé: famously, the new translation of The Famous Five is written with passé composé. Younger people tend to write their autobiographies using passé composé, apparently. Other than that, using passé composé would probably feel informal to most (adult, I guess) people.