And about the "Level-draining" poison - sorry, I don't like this idea. I fail to see how such a heavily magical effect could be "brewed". Lets keep Level Drain for spellcasters and magical monsters, ok?
If you think it will unbalance the game, so be it.
But I disagree your opinion about "brewing" level draining poisons. I can imagine some ways how such a poison could be brewed : an assassin could use the blood of a vampire or some illithid serum for this.