These songs were sung on glee?

but who sings the originals? the first is "confessions" it was from the episode where the boys and girls compete against each other with mashups of songs and the song the boys mashed it with was "it's my life" by bon jovi. also, who sings "halo" from the same episode? thirdly, the song that mr shuester sang to rachel in the episode where they had to sing a duet with someone and she was starting to show feelings for him. he mashed it with "don't stand so close to me" by the police. i know i've heard that song before but can't think of who does it. anyone know the answers?