X and Y axis crossing

Will the X axis always be at the bottom of the plot area? Will it ever be possible for the values on either Y axis to be less than 0?

When you click "X axis crosses at 0" for the secondary Y axis, that setting will apply to where the secondary X axis (even when not displayed) crosses the secondary Y axis. Assuming the two conditions I asked about are true, I think the setting you need is to fix the y axis minimum (for both primary and secondary Y axes) to 0.

I must have mis-typed. I was not referring to setting the "axis crosses at" property. I was referring to setting the axis minimum property (different from the axis crosses at -- should be at the top of the dialog) to 0 (be sure to check the "Fixed" radio button before trying to enter 0). Of course, this only works if my assumption that the values plotted on each axis will never be less than 0.