Green yellow purple was used for distribution, black blue black for residential wiring at least where 5 core cable was used. Other than that phases could be about any color even grey and red (usually neutral and ground). Where conduit was used people typically pulled all 3 phases the same color.
In residential wiring green, yellow and other colors were often used for switch legs, travelers and other special purposes.
The double insulated ground wire seems to be typically German, Austria uses single insulated as far as I know.
Yes, aligning devices in the boxes is somewhat tricky. I guess the worst thing is 6 2.5mm2 wires in one box for daisy chained sockets. Some time I'm going to try Italian wall boxes with Schuko sockets, I think that might be easier to wire.
