Correct term for ADC process
You definitely need sample+hold and quantization in there.  Encoding is going to be a bit dependent on what type of ADC you have.  A successive approximation or pipeline ADC usually quantize one bit at a time, and no extra encoding is required after that.  However, other types of converters do need some extra processing.  For example, flash ADCs need to convert the outputs of 2^n comparators into a single n-bit number.  This would probably be best described as encoding.  Delta-sigma ADCs also have to do some sort of postprocessing/filtering to convert a high speed 1-bit wide stream into slower-paced samples of greater bit depth (i.e. 16 bits).  However, this would more likely be called 'decimation' or 'sample rate conversion' than encoding.