blackdog

I have 2002 4wd 4runner. I going to attempt to flush the transmission. I know that the system capacity is around 15 qts. I drained 5 qts out of the pan. I also changed the filter and refilled the pan with 5 qts. Now i am at the point of actually flushing the system. Now, do i need 10 more qts. since i have already added 5 qts., or do i need to flush with 15 qts? Does the fluid i replaced after the filter change mix with the old fluid? Also, does the return line come out of the bottom of the radiator on the drivers side?

Thanks,
Jeremy