Where can I find regulations in different countries for flight level rules based on direction of flight?
Every country's Civil Aviation Authority issues an Aeronautical Information Publication (AIP) as part of their Aeronautical Information Services (AIS) which contains the information you are looking for. Most likely the information about Flight Level rules will be contained in the GEN (General) or ENR (En-Route) section. For Europe, most information from the AIP's can be found through the European AIS Database