http://naruto.wikia.com/wiki/Shadow_Clone_Technique

yeah, i'd say it is divided evenly.

maybe the 2 rasenshurikens rule is assuming that he's only going on 1/3rd chakra, so even though he gets triple chakra after disbanding the clones, it wouldn't count towards another rasenshuriken because he wouldn't be able to form the three clones needed. i dunno.

naruto did 3 clones (were there more?) in the kakuzu fight, and he did a rasenshuriken, then instantly pulled another one out right after it. so when he's in sage mode and has just been refreshed with a new clone's sage chakra... i don't think it matters.

all i care about is reading next weeks chapter...