Some answers to common questions and clarifications of some details:

1. Don't forget to CC the ref when you send your letters!
2. You've been given a large number of contacts. While you don't need to write everyone every week, most people like getting letters. I've found that the game runs pretty well if everyone aims to average three letters a week. Though you can often get more done if you talk to more people...
3. For this scenario, your first contact also have you as a contact. But you are allowed to exchange contact information with other characters. Or ask characters to tell others things. And you may get an introductory letter out of the blue...
4. Assume a technology level roughly equivalent to 18th century early-industrial Europe. Though someone might tell you about the exceptions...
5. Your character sheet should have everything you need to start inventing your character. Feel free to ask if something isn't clear or if you're not sure if something is allowed. (The answer is almost always that it is allowed.)
6. Narrative authorities can be taken literally. And metaphorically. As long as it's clear to the ref what you intended to invoke, it's within your authority to describe it.

If there's anything that isn't clear or that you don't understand, please ask. I'm trying to develop this scenario so that other people can use it to run Callisto, and every clarification I can make now will help many people down the road.