For a large, highly complex project with significant risk, which elicitation technique should be used to analyze input to and output from the product?

Company A would like to enter into a new market. The business analyst has been assigned to a project for which nobody in Company A has any prior experience. The project manager has asked the business analyst to assist in resource planning.
What should the business analyst recommend to the project manager?

A few months into a project, the business analyst determines that the costs are exceeding the perceived benefits. The business analyst wants to address the possible risks of having to cancel the product.
Which of the following documents should be used?

Company A has initiated a project to update their online ordering system. The business analyst has noticed that the purchasing department, a primary stakeholder, is excluded from the list of stakeholders.
In which reference material can the business analyst find information about the missing project stakeholders?

Once the requirements are compared to internal and external quality standards, what should the business analyst do next?