Technically yes. Over the five nights, you hear snippets of William Afton leaving his daughter alone with Circus Baby. Due to his ignorance, she is left alone and dies
No, but the ending implies the character has been lied to and manipulated throughout, and a secret ending has the main antagonist attempting to emotionally manipulate the player.
on night five of sister location, the night begins by turning on the lights to make sure the animatronics are there but you are shown the silhouette of dead technicians hanging on the stage.
A character explicitly says, "I kidnapped you", and she's correct. Also, the abduction of children is a major theme throughout the games, and all of them die.
It is implied that one of the animatronicd contains the spirit of an adult woman who was a mom. This is never explicitly said or shown in game, though.
No, but expect to see lots of debates in fandom spaces over what gender the robots are, as is typical for these games; Funtime Foxy is particular is referred to with both he and she pronouns.
A character is literally gutted alive,and later shown rotting (in 8-bit), but it's mostly implied; the screen flashes red, and that's it. However, as is typical of these games, horror elements are strong throughout.