unless i misunderstand what you are asking have a look at the specialization techs most of those upgrade various stats such as range, rate of fire accuracy i believe you would be able to upgrade most of the stats using similar tags.

Ship Components are not linked into the PrerequisiteDefs table, so no you can not add Pre req's to components. You can try adding in the include to the schema, I know from testing schema dont seem to mind having new includes added, that however doesnt mean it will work

My bad, it is. Sleepy eyes betrayed me!

Edit:

Looking at how the schema is built, you are correct in you assumption it a limitation atm. (Same with trying to make improvements obsolete with tech, although this doesnt throw errors up, its just ignored)

With 1.8 you could trying looking at the way they use the leveling up, not really what you want but there is a possibility with it. (Level up uses the same stat table as components).

So you could for example make a Massdriver that say adds x% per level. A Beam that add y% per level ect.

ExpPoints - Grant x amount of xp.

ExpBonus - Is the DLC Effect.

ExpValue - Is the Value of x Target.

ExpPointsCap - Not sure on this. As I was not aware there was a Cap (Got a Ship atm lvl 17)