I teach that you should seek to learn from competitors; obviously never copy another business's idea or what they are doing, but you can absolutely learn from their mistakes or see what they are doing and discover ways to improve it. All of that analysis belongs in your business plan: make sure you have your competitors under the microscope and make sure that is a solid chunk of your plan. That is some of the best research and information you will gather about what will make your business successful in future.
Organization and content of the business plan will evolve as it is prepared. For example, if the driving force of the plan is marketing or sales then a preponderance of the analysis and plan_of_action section will be more up_front and sales oriented in tone. With business plan's the world is your oyster; think from the center out to the edges and think outside of the box.