yup, it depends. When I first found this forum I spent about 2-3 hours a day, maybe more, for a week. After that when many things became clear to me around 30min -1h. But of course it depends on your free time, because, as a matter, of fact there is so much useful information in here, that it just worths to read it.
it depends, i often spend 3 hours or more on DP when it's weekend, and less than 1 hour when it's weekday
Prob 3-4 while doing website work / SEO. Not much else to do when you get off work at 3am and go to sleep at 7am.