So many questions I want answered!
I have a few uninformed guesses for you
Did they have sex? No - her skin had grown around the seat - I doubt she moved off it at all
Did she watch TV? It's possible she had a radio or portable TV but it is also possible that she spent most of the time in a stupor.
Did she change clothes? I would image not - if she was too quasi-catatonic to stand up off the toilet I doubt she was much concerned with changing clothes.
Is her boyfriend a fucking moron? He probably has social challenges of his own, if that is what you mean.
Did anyone else know about this? I would guess not.
Where the hell is this womans family? Some people aren't in touch with their families.
How did she sleep? Sitting on the toilet. I would guess she either slumped forward or leaned back against the cistern - it is possible the toilet was near a wall and she would have had another support to lean against.
How did she bathe? I would imagine she didn't.
.....