The answer could be quite simple: do whatever works best for you. I e if it gets things done, it works. I wouldn't bother about the calendar being cluttered, if it makes you Get Things Done. What David goes against is trying to foresee what will happen when, because things change and then you have to reschedule - you're *not* getting things done other than maintaining your calendar.
Same goes for Outlook handling: if you find yourself doing too much rescheduling, go for a day reminder - if that on the other hand sometimes leaves you with no time left, make a proper appointment, and treat it as holy (i e let even the president wait ).