Kegare Naki Bara Juuji always send a chill to my spines, one of their best songs imo. Edit: It's the song at 3:13 it even played for more than a minute
No (although Cathy and Rill have ever provided the vocals earlier before Luna and Rena joined) Luna is currently in charge of Ariabl'eyeS along with Lyse (the bassist & composer) since Rena has health problems that prevented her from singing again (Yuzuki Risa overtook her temporarily until she becomes fine again, I guess).