A plan is not etched in stone. It is subject to change. As time goes on, things change in this world and businesses like everyone else are subject to change. A good plan will reflect changes that a company has to make to keep it competitive and successful. Where can you find samples of a business plan for a small business? If you go into any of the search engines such as Google or Bing and type in "samples of a business plans for a small business" you will find websites with this information. This is why it is important that a small business should have a business plan. If you look at those small businesses that are successful, you will find that most of them all started with and have a plan for their business.
Who is the ideal customer for this product or service? Really, ideas for business are a dime a dozen. You often hear people talk about a great business idea they have, but they rarely back it up with any kind of proof that a customer exists for such a product or service, and that that customer would be willing to pay. Try to be specific in profiling your buyer. For example, does your product or service cater to men or women, or both? What age groups or income levels does it service/attract? Are there any geographical areas that your product or service would supply?