1. IF you subtract the capital cost of the hydroponic system, then I would say it costs more to grow organically using quality products.
2. Never used teas, but I am confident the pre-fab products work fine.
3. It is not less potent, and, depending on the strain, organic product can be superior in my experience.
4. Get some Pro-Mix BX, amend it with worm castings, guanos, and whatever other organic amendments strike your fancy and you need merely add water for the life cycle of the plant.
The benefits of using a hydroponic system are: automation and increased yield. If somebody thinks they are going to take a 4x4x4 cube of organic mix and match the yield of a 4x4x4 rockwool cube, I would have to see the evidence of it because I do not believe it to be possible.