[djmtsu]

1) Anything higher in designation is basically a 'newer' blend that meets or exceeds the previous blend. So Dextron III is what you want to use.

2) The easiest way to flush the system is to remove the return hose from the pump, route it to a container, and turn on the car, move the steering wheel lock to lock a few times and it will be all gone, of course, that is not good for the pump since the fluid lubricates the pump. You can turn the pump by hand instead and do your best to get it all out.

You can add an inline power steering filter to the return, drive a while, then change out the filter, or remove it all together.

Have fun! Don't forget that you need to 'bleed' the power steering system after a full fluid replacement. Turn the wheel lock to lock a few times, check the level, do it again, repeat until it doesn't have any 'dead' spots and it stays full.