Wattage : This basically means that how much watts of electricity your fish finder will consume . Nothing more technical into that. It is measured in terms of RMS or root mean square. wattage is directly related to performance. More wattage means more better performance. Less wattage means less performance.
Transducer frequency : Frequency of transducer determine at what frequency you will transmit and receive sound. It might vary from one value to another value. You always send a fixed frequency sound signal using normal technology fish finder. A high frequency fish finder produces much detailed data and vice versa.
CHIRP : It stands for Compressed High Intensity Radar Pulse. It basically means that instead of sending a fixed frequency of sound wave, it will send a sound wave that keeps on varying between a certain range in order to produce better tracking results. Fish finders that have this technology in them are the most advanced ones and expensive too. But a complete value for money product and no compromise in terms of technology.