You really need to read the many posts out there on DWC because your questions don't have single answers.

Is the yield higher than soil? Yes or no, depending on the capabilities of the grower and other growing conditions.

Do you need to change the nutrients every day? No. Depending on your total nutrient volume, whether you're using a recirculating setup, nutrient concentration, etc., about once a week is common for a nutrient change (but you will have to top it off every day or two depending on volume).

How much water does it use? Anywhere from a few gallons to 100+ depending on your setup.

Can I get rid of that chemical taste? Yes, just flush your product for the last few days to week of flowering.

DWC is a nice setup because your plants sit in an aerated nutrient solution 24/7. This allows them so take in as many nutrients as they desire because they don't have to wait for availability. Once you get it set up, there is little maintenance aside from checking pH, TDS, and topping off your reservoir each day. I would have to say that the only disadvantages to DWC are the initial cost in dollars and time for your setup.