The orange person is Rei Adachi(足立レイ)! a mechanical girl! Her famous songs include "netsuijou(熱異常)" and "Utau bot(歌うbot)" so be sure to check them out!
no.They are Vocaloid / UTAU characters. I also like Touhou Project, However, this song was arranged with "game music" in mind, so there may be some similarities.