Who should see your plan? All the players in the company. Firms typically keep their marketing plans very, very private for one of two very different reasons: Either they're too skimpy and management would be embarrassed to have them see the light of day, or they're solid and packed with information . . . which would make them extremely valuable to the competition.
The plan should cover one year. For small companies, this is often the best way to think about marketing. Things change, people leave, markets evolve, customers come and go. Later on we suggest creating a section of your plan that addresses the medium-term future--two to four years down the road. But the bulk of your plan should focus on the coming year.