I'm doing WBTB right now, and of course I checked the DV wiki, but it didn't answer all my questions.
I get the general idea, but I wonder if anyone can answer a few questions for me?

How long is too long to stay up?

What should I be doing? As in standing around, sitting, light exercise?

Will I know when I have waken up enough? How can I tell?

At what time should I wake up? I know it has to be before or after a REM, which I can do fine, I usually fall asleep around 12:30-1:00 and wake up at 3-4, but is there a graph or something that shows me when REM cycles occur?

Thanks in advance. Again, I already read the wiki and tutorials, but they didn't clarify enough for me.