There are heavy bites and big wounds in all movie. The first attack seems like a bite to the neck and a big chunk of flesh is bitten off, it's not clear if it's the neck, the throat, or the jaw.
I guess a lot of women are brutalized, but it's never in a sexualized way. They do appear in numerous states of distress and undress, too, but everything is just focused on the overwhelming fear and panic.
Not really gaslighting, but all main characters are kept hidden by the police what's actually going on in the building and that they are being left to die
Physically no, but the entire thing is so traumatizing for all the characters that it could be well like being subjected to torture. Definitely big traumas
There's a...thing that's supposed to be a young girl who has SPOILER transformed into a really terrifying creature almost. Implied it's the young girl they were talking about. Well, she's in her underwear, but her chest is bare. It's not sexualized, it's just a naked body, but it could be upsetting, especially cause shown very clearly on camera.