Hello Tesseract,
If your thinking of growing multiple plants in the same system, pH,
nutrient type, and concentrations is only part of it. It's all the environmental factors as well. Understanding the environmental factors of a particular plant only takes a few minute if you know where to look for it and what your looking for. Pictures of a plant growing will be ale to tell you things like is it a bush, vine, or even ground cover type plant, what type of leaves it has, as well as how big it will get. The size of a plant above ground will also tell you how big the root mass will get, and the type of top support/trellis it will need if any. How big the plant gets and leaf size will tell you how much water the plant will drink up daily so you can size your nutrient reservoir to accommodate these needs.
Things like "how easy is it to drow flowering vegetables vs. Greens" is plant specific, not type like flowering vegetables vs. Greens. And again is easy to determine. Plants that tolerate wet feet better than others are what you would probably consider hardener to drown. But it's not called drowning, it's suffocation. There are two things to look for when determining how easy it is to suffocate a plants roots, your looking to see if the plant can tolerate wet feet, and/or more importantly if it needs well draining soil. Then you can take these things into consideration when deciding what type of growing media to use, as well as designing the
hydroponic system around these needs. Suffocation isn't too much water, it's a lack of sufficient air and oxygen to the roots. Just like a human, you will be fine submerged in a pool of water unless you couldn't breath, then you would suffocate ("drown"). To find out how much air/oxygen the roots of a particular plant needs, you just need to find out how well it tolerates wet feet and/or what type of soil conditions it prefers.
Beyond just soil conditions, you also want to find our other environmental factors that will affect the plant like is it a spring, summer, or fall crop. Is it a continuously fruiting plant or does it fruit/flower near the end of it's life cycle. Humidity preferences, does it prefer full sun, part shade, mostly shade etc.. The planting time and growing zone (northern or southern crop). These things will tell you what type of light requirements it needs, temperature preferences and how heat tolerant it is, whether it's a cool weather crop or warm weather crop, fruiting cycles, etc. etc.. And all this information is easy to find on seed packages and online from seed manufacture websites. If your not already familiar with growing the plant, it only takes 10-15 minutes to research all you need to know about a particular plant to design a hydroponic system to accommodate it's needs. If you plan to grow multiple crops, it will also tell you what you need to know to see if they are similar enough to grow in the same system, or if their better off separated into separate systems.