About the Vyrewatch, they are people (mayority Iycines) who lived in Hallowvale (AKA Sanguinesti modern day) that couldn't escape from the Zamorakian forces led by Lord Drakan. Most of them were forced by him to become a kind of slave, AKA a vyrewatch, some of them did it because they thought they would be granted by Drakan. However, they all turned into Vyrewatch, probably by a kind of blood-process, but that's unsure. Those who were enslaved by Drakan, made an agreement with Saradomin, he would save their souls, so they wouldn't get corrupted, what did happened with their body and mind. The Iycines and humans that got across the Salve, made a Columbarium in Silverea, the place where now Paterdomus stands. It was (and still is) a place where the souls of the enslaved Iycines could be freed. As a thank, the soul would grant an adventurer who slays his corrupted body a key, to open a lock which contained their belongings, as a gift. To me, the theory of Vyrewatch copying Dragonkin is like saying that the Gnomes are copying the Dwarves, because they are both small.