It's the Ruff Ryders on the DMX musics,
they ride on motorcycles.
This is R-U-F-F R-Y-D-E-R-S!
"Pounds from" is something like
when you have to do something and
you don't care much about the feelings of the other people.
"Pounds from my brothers, cause I need to leave." means "Sorry for my brothers, but I have to leave (now and I don't care of what you're saying!)."
It's the contraction of the words "it is" so it's the same as "it's".
Itz clean, nigga! The cops are gone!