what does that mean???

hi there..
i’ve heard these words and expressions in the song
(lady marmalade),but i have no idea about the meaning!!
1-creep
2-livin his grey flannel life
3-gitchy gitchy ya ya da da ( i don’t know if it makes sense or not)
and what does it mean (she bangs) in ricky martin’s song??
the last Q what does (diss) mean in this part of the song (survivor):i’m not gonna diss on the internet?
thanx a lot
bye bye