The Duke of Chalced's Throne Room *Spoilers all books incl CoD*

['thul]

Silver was stated to be directly linked to Dragons intelligence. So it doesn't really humanize them so much as make them smarter and wiser. It also appears to be linked to their ancestral memories, so that would explain how his vocabulary improved.

Position-wise it could be, but at the same time, it was quite far away. Its hard to say not knowing how far apart the various cities were.