Nicely written, and you are correct, toba is indeed one of the largest supervolcano in the world eruption wise, being beaten only by yellowstone (probably). Samosir island is indeed growing, but as an Indonesian, as far as i know, the growth is quite slow so its still relatively safe for the people there and it's surrounding regions, hopefully it wont be active for a long-long time
RE: a controversial cataclysm from 75,000 year ago