GetAdapterPacketQueueSize was added on the customer request. Personally I never used it myself in WinpkFilter based projects. But it may have sense to use it an example when you have a single thread reading packets from several network interfaces. In this case you can use this call to determine the interface with the largest amount of packets queued and read that amount of packets in next API call.
NdisrdRequest is a wrapper around NdisRequest NDIS call. It only needed if you need to query some specific information from the network interface.