re: Poker & how often can a good player expect to win?
This is where the advantage of multi tabling comes up, if you play 2 or more tables at once it is much easier to balance beats by winning in other sessions. I think a winning player should be able to win money just about every session (Bostonguy, the 80% sounds good).
Generally, you should have a goal of profiting from every session, but you should be happy if you lost very little and be expecting to loose a bit now and then.
In terms of BB/100 hands it really does depend on the level and the player. As I went broke earlier, I have dropped down to 2c/4c tables on Party and I am making good money off them, all you have to remember that in no limit you can be loosing for hours and then with a couple of hands make back the losses plus a nice profit. The game at the level I am playing is poor and I have been able to adjust my reads, so I am making close to 50BB/h by 3 tabling it.