"Is the company consistently profitable or not?" and "Are revenue and profits growing over time, stable, or declining?" are very important questions to answer, particularly if stock grants are part of the compensation package.
For developers who work on products, getting a sense of whether the product of the team you'd be joining is a core part of the business versus speculative (i.e. stable vs likely to have layoffs) and how successful the product is in the marketplace (teams for products that are failing also are likely to be victims of layoffs) are also very important to understand.