1) Pretty much all orchid growing is hydroponic, as the plants use the medium for mechanical support and do not get their nutrition from it, instead taking it from the nutrient solutions we use.
2) Most growers will tell you that having a common nutrient bath for multiple plants is a bad idea, as it becomes an excellent vector for the spreading of pathogens - fungi, bacteria and viruses. No commercial orchid grower is going to assume that level of risk with his livelihood.
3) You are correct on the faster, better growth though. Having a constant supply of water and nutrition always beats an intermittent supply, and - all else being correct - gives the plant the best opportunity for growth and blooming.
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