in my experience, renzo teaches whitebelts too, its just depends on if he's there or not. he was training for adcc, then the bj fight, so he hasnt been there to teach much recently and i dont know where he is now - but that's the price you pay for training at the academy of an active competitor. there have been stretches of a couple weeks when he teaches every night, but that's not the norm.
as for the rolling, the whitebelt class is an hour with no separate randori, but there definitely IS randori. to clarify, the blue belt classes are an hour, then there is another hour of supervised/structured randori (i.e. timed rounds, little rest, one after the other, instructors busting your ass to get back on the mat)...that is what you don't do in the whitebelt class. but, no one will stop you from staying after your class to train as long as you want, you just need to move over to the side of the mat where classes arent going on. You also won't be training with the whitebelts until you're a blue belt, just until you get a couple stripes on it.
anyway, sorry for the thread hijack...you should probably train at both places for a week and see which one you like best, it would be much better than listening to what anyone posts on a message board.