Thanks for getting in touch.
To scale the volume series, one option would be to apply high range padding to your y axis for the volume series. (setRangePaddingHigh(U rangePaddingHigh) on the axis class). You could then either provide a custom set of tick marks, or use a ShinobiChart OnTickMarkDrawListener implementation to not draw tickmarks which are greater than a given value. This would prevent tick marks and labels being drawn all the way up the y axis.
To set the alpha on a column series you would need to set a color, with an alpha value using setAreaColor(int areaColor).
The tick marks for an axis will automatically be drawn on the same side (of the chart) as the axis to which they belong. As such you would just need to make sure that you set your y axis to be on the reverse side using the setPosition method of the Axis.
To align the y axes of two separate charts, you could make use of ShinobiChart.OnAxisRangeChangeListener implementations.
ShinobiCharts for Android does not directly support drawing tick marks and labels inside the plot area. That said, it can often be done with a little work but it can be a little fiddly. The two usual approaches are to use a negative tick gap, as you have mentioned, or to use the ShinobiChart.OnTickMarkDrawListener to offset the tick marks and labels as they are drawn.
I hope that this information helps you,