The decision to drop a product (or line extension) should not be made solely on the basis of which quadrant a product or SBU lands. Some of the issues you may want to consider are how is the market defined? Do you agree with this definition? Is the extension a relatively new product? Is it gaining or losing share? Does the extension provide any synergies with existing products? What other possible purposes does the extension provide?

Volume discounts, promotion, sales force, and sales (product turnover) for a retail channel will all help improve your product's support and shelf space.

The estimated unit sales are the sales you or your team estimates you will have, and are supposed to be entered by you. They are not generated by the report.
The report can show you what would happen if you sold a given amount with your current decisions.