Heh, yeah, we've been working on technology lately, and one of the things that each technology can have (in addition to tech prerequsites, of course!) is scripted requirements... I imagine most techs wouldn't have any of these, but imagine something like "you can't research black-hole cannons, no matter how much Physics tech you have, until you have sent a ship with a science lab component within 1 AU of a black hole"!
Also, the way we're doing techs, you don't so much have "levels" as you just have points accumulated in various areas, with techs and components and buildings and the like branching off at various point values, say, 500 pts in Physics might unlock Lasers.
Another thing that techs (and anything else you can unlock, such as components or buildings) may have is "visibility requirements" - this would be especially useful for mods with randomized tech trees! E.g. you might know from the data files that getting lasers requires 500 to 1000 points in Physics - but how much exactly? You might not know until you reach, say, 250 points, and you see how much work is really ahead!
As for flavor text, that really depends on how much time we have to write that stuff!