Confused with DWC

Greetings from Ireland! Im a noob to hydro, only ever grown 2 plants before years ago and both were in soil.

I plan on growing 6 Duch Passion Power Plants in DWC but still have questions that I havnt found answeres to through research. Heres what im confused about:

1. How often should the nutrient solution/water be changed with DWC?

2. How do you actually change the nutrient solution/water, as in what do you do with the plants while changing it? Is there a special way to drain and refill?

3. Il be using 600w hps throughout the grow, and may be using 12/12 throughout the grow. Could I expect 2 ounbes per plant this way?