The size 6 rule is a FIBA change that actually came into being with the same set of rules as when the possesion arrow was introduced. Basically all womens games are meant to be played with a size 6 ball.
Interesting to note in the new list of changes in the new FIBA rule book, any player now "flopping" to dry and draw a charge foul WILL geta personal foul for blocking called, and a technical foul as well for trying to intimadate the referee.
ALL technical fouls will now be 2 shots and posession, which should stop some of the confusion.
The rule changes also state that 55 is no longer a restriction in national compeitions as far as player numbers goes. Not sure if that means the old 4-15, 20-25, 30-25, 40-45, 50-55 are gone, and you can basically have any number.