1) This will not bode well for anyone that does it, as the Haniwa's cursed spiritual power will seep into the person they are nearby, infecting their nightmares and, with enough exposure, even give them hallucinations of seeing Haniwa faces where normal faces should be.

2) Well the Moon Viewing is a busy time for mochi sellers in general, so she'd actually appreciate the help, though she won't be able to pay Aerith much (though she will get her fill of mochi, if she likes). The bunny costume will be appreciated, and she thanks Aerith for her respect (somehow). She is not willing to part with her ingredients, however, saying the work it takes to gather them is far more than simply helping out at a mochi stand