excelent piece of advise - one thing I find quite hard (impossible?), though, is to have EVERYTHING explicitly spoken/written: there are just so many variables out there, you'd probably lose a lot of time sketching things down - and still not covering the bases that will turn out to be problems...
It's definitely impossible to plan for every eventuality, but that doesn't mean that doing some planning isn't useful. Ultimately, start-ups are very resource-constrained, so you have to do what you think matters most and hope for the best. If you at least have a good stab at answering the questions outlined in the articles (and the comment by Sebastian), you'll be a long way ahead of where you'd be with no planning.
