Strategy _ similar to business strategy, marketing plan will capture strategies required to support your business strategy. For example if your business goal is to achieve 20% increase in sales, your marketing strategy would be to 1) introduce new product, 2) increase price for premium offerings, 3) recruit more distributors and offer commission scheme and so on. Strategy is king. When you can see your business in totality, I can assure you that you will find it easier to manoeuvre. Marketing plan is the place to address all these issues.
Ideas _ people said the more you talk about your ideas the more refine it becomes. I think this is true. Did you ever experience when you talk to more people you generated a lot more ideas? When people give you feedback it triggers another dimension of your ideas? If you are, so where do you keep all these ideas? It should be in a marketing plan.