Castor oil is a vegetable oil derived from the castor bean seed in its purest form. It is colorless, odorless and tasteless.
Encoding globally available pointers helps protect them from being exploited. The EncodePointer function obfuscates the pointer value with a secret so that it cannot be predicted by an external agent. The secret used by EncodePointer is different for each process. A pointer must be decoded before it can be used.
The & symbol in a C++ variable declaration means it's a reference. It happens to be a reference to a pointer, which explains the semantics you're seeing; the called function can change the pointer in the calling context, since it has a reference to it.