@changelingcritter I love these questions! They've got me genuinely interested in developing Dot as a character 😆❤️.
1) Since Dot is a Mannequin creature from Silent Hill, I would assume that, rather than having a brain, her function and behaviours rely on other people's belief in her and perception of her, much like gods in fantasy fiction. Like in the SH lore, she is in fact just a manifestation of someone's wild psyche and libido; she's just the sillier, more pet-like version of that concept.
2) As per point 1, since she is *technically* imaginary (but made real through belief), she currently feeds and sustains herself off of other people's sexual arousal and... Fluids... Much like a succubus of sorts. This is purely because enough people believe she does.
3) While Dot lacks vocal chords and any ability to speak or traditionally eat, one *could* consider both her vaginas "mouths" of sorts since they are used to feed her with people's sexual appetites and pleasure. She also occasionally makes a little expressive "queef" in response to verbal communication.
Anyways, hopes that answers your (very likely rhetorical) questions!