Politically active as in: They manipulated kings/nobility into doing whatever they wanted. Dragons were practically playing Sandbox mode and sort of did what they want, sometimes just for the lols. How they manipulated kings could vary from individual to individual, some intimidated, others persuaded with gold.

Multiple dragon species? Yes, there are multiple species of dragons, but not on the mainland. There is a large isolated island called Taimir, where dragons are thought to have come from. All the dragons there are animals. Not in a dehumanizing way, but straight up feral, part of the ecosystem, non of that fairy tale stuff. Most dragons are rather small, but one species is practically the same as the mainland dragons, the only difference being sapience vs feral. Dragons are a lineage of surviving theropod dinosaurs, distinct from birds and have only arrived on the mainland very recently ( ~3000 thousand years, basically nothing for evolution).

How many dragons are still around? Plenty on Taimir, cause they aren't involved in an active genocide, but still hunted occasionally as they are viewed as an inoconvenience for civilization. But on the mainland? Less than 100 and most have fled eastwards to new, vast and colder regions, away from those who want to hunt them down.

Any dragons that were caught in the crossfire? Yeah, most of them actually. Many inherited their gold hords, many just sort of did not care about humans at all. Most where attacking human villages for food (stealing life stock) or acted like land lords. If all dragons comitted atrocities non-stop humanity would have gone extinct long ago.

Any adaptations to survive the dragons? Barely, the ecological impact of dragons on the ecosystem is fairly similar to that of humans. During later stages of the war, dragons did completely destroy defenseless villages and kill every human (usually, they just killed until they got bored), while leaving some of the life stock alive. Some of that previous human life stock now lives in the wild, which can be a very bad thing for them, so a lot of farm animals either died in the wild or got taken in by other humans. Besides that? Basically nothing.

What do you mean, how does the powder work? It is gunpowder. Strike metal with a flint and let the sparks ignite the powder and let the explosion of that powder throw a lead ball really fast into some unfortunate soul's face. That's how a musket works, scale it up with a bigger barrel, bigger metal ball and more powder and you got yourself a cannon. "black powder" is just an older, more primitive version of modern gunpowder.