I think H's statement about P hating herself is simply a natural progression of that scene. P brings up Lena which sends H into a rage. Following that, H gives retribution mercilessly. It really isn't fun anymore. Anything to get her to leave. I think it may be simply the first thing that comes to his mind in that exchange--"because you hate yourself." Finally, she leaves him alone, and he's free to hate himself in solitude.
Lena, obviously, is the woman who burned him. It's open to interpretation, but maybe, possibly, she's dead too. Maybe he killed her. Maybe she killed herself. This question is best left unanswered. That's what makes it great.
The rest of the questions are the same. Your guess is as good (maybe) as mine. The best art always leaves you asking--and as Sarah Kane said, "subversive both in form and content."
Give yourself a break and treat the play for what it is. Realize there's truth in it, resist the need for explanation, ask rhetorical questions, and answer them yourself. Your experience may pale to someone else's. Abandon hope of understanding. I mean, can you really say you understand life on this planet? I'm sure you've seen characters like H in real life. What causes people to be attracted to them? In the second scene in Phaedra, P tells the Doctor that H is a popular guy. The Doctor asks "Why?"
Hippolytus asks "Why" several times in the play. He wants an explanation as much as we do. He never receives a satisfactory answer. 'Nuff said.
Archive 6-10-2002