Five concise questions for the entrepreneur

I’ve been contemplating the questions that concisely define a business.  These questions aren’t quantitative and are no substitute for a business plan, but any entrepreneur (or any executive, for that matter) should be able to answer them confidently and without equivocation:

1. Who are you customers?  (or, how do you know whether or not someone is your customer?)
2. What products/services do you sell?
3. Why does the customer buy your product/service rather than making/doing it themselves or buying it from someone else?
4. How does your business generate a positive cash flow?
5. How does your business generate value beyond revenue from sales?

So, gentle reader: what essential question would you add to this list?