QGIS 2.6.1 - Formatting pie chart

Question

I'm making a map for school GIS course coursework. We must use cartodiagram/chart for map and I have an idea to make a map, that shows lighthouses and their light sectors as pie chart. I have managed to extract data from large pdf and import it into QGis as csv.

In that table, I have described light sectors as (5+1)*8=48 values per lighthouse (5 colors + no light, for maximum of 8 sectors). Data starts from north and continues clockwise. In QGis, I can set that pie chart starts from up (north), but it lists sectors on chart counterclockwise and changes something else(?), so I need to flip all pie charts horizontally.

Other question, is it possible to add transparency/alpha channel to pie chart color. If it is possible, how could I achieve that, if not, what is then workaround? Currently, I'm using simply black as placeholder.

Final, but not important problem, how could I bring other layers front of charts? Setting diagram priority nor layer ordering didn't work.

P.S I'm non-native english using non-english QGis and computer, so some exact names of functions/objects might be wrong.

Clarifying questions:

1. How to add transparency to pie chart pie?

2. How to transform (flip) all charts at time?

3. How to change chart rendering order?

Edited to remove other questions. Pie transparency is most important for me currently.

Answer 1

I forgot to tell earlier, but I found workaround. In QGis it is possible to change chart's opticality. I changed opticality to around 50% and replaced empty sectors (black on image) with white and white with light grey color. That way white and empty sectors remain distinguishable and white lights are visible on open sea (which has white background).

To fix wrong sector location, I simply added list reversing function to Python script, that generated csv.