1.) It's totally up to you. Some guys like watching 10min of a vid, some like stuff like meditation (have a look at Eric's vid released last week).
I always watch at the hands I marked the last session, and I think that's a good thing too, because it forces me to mark hands during the session:)
Just try some stuff out, anything pokerrelated. Compare poker to any kind of sports. Before the match you need to warm up. Whether you just run / do any kind of other sports (e.g. in my table tennis club we were used to play football for warming up:D). If you find anything which you like doing, that's probably best:)
2.) I tried out writing some things down before starting a session: One of it was Start time of session and End time of session. It's like setting an alarm. If you start at 4 and set the end at 5, it should be more difficult for you to just continue playing without a reason ( It's okay to say: Hey, I'm playing really well atm, I keep on playing). Therefore you can write down after your session the time you actually finished playing.
3.) Almost same as in point Nr2. If you say you got this stoploss , that's fine. The most important point is that you think about your game when reaching your stoploss: "Oh, I lost 5 BI. Am I still mentally fine to keep playing?"
If your answer is yes, keep on playing should be fine. If it is no, stop playing:)
4.)gr8:)