When do benefits (health insurance, travel, etc.) start? First day or later?

Health insurance and other benefits start on day 1, as does travel for you. For your spouse/kids, it may take a few days to get them into the travel system, but it's fairly quick as it's the same department as benefits that gets you in. For your parents, it's the pass travel department that adds them, so it may take several weeks before they'll be in the system to non-rev.

How is seniority determined in class... age, SSN, something else?

Thanks

It's by age.

Cool, thanks