Rates: on average €0.25/kWh
3-phase drop: is standard for every premise, even a 1-bedroom apartment has it
shortage in winter: no, Germany has been a net exporter of electricity for ages. Talks about shortages are usually corporate FUD.
To clarify: there is no tax euro spent on the electrical infrastructure. The conversion to renewable energy is financed by payment guarantees, which in turn are financed by the consumer. http://en.wikipedia.org/wiki/German_Renewable_Energy_Act.