The culture will be set by the behavior of the founders rather than simply what is written on paper. I would however suggest that you intentionally think about your company culture and have it be done by design as opposed to default. Do write down what are crucial values to you and those that the founders share – and believe to the deepest level of their being. Your vision might change but your values should not. Once you write them down, you have to fully align your actions to them and hold people (including yourself) accountable to these values. Measure them in your HR reviews and interviews. Never cut corners on values. I have written more extensively on this in my TechCrunch article titled “Culture Eats Strategy for Breakfast” which you can find in the articles section of this site or just go to http://www.d-eship.com/articles/culture-eats-strategy-for-breakfast/