The original soundtrack of Durarara!!
No, the reason why people make Izaya & Shizuo look like a couple is because of Erika Karisawa (that female character in the series who is an otaku/fujoshi). She said in an episode that they were like a couple, but that's just her saying things because she's like a yaoi fangirl.
...and your last question is unclear. Are you referring to this FC/group or still asking /more/ about Psychedelic Dreams?