Re: Lem rune
They don't drop in Normal. The earliest is in Act1 Nightmare, but the odds are pretty poor that early on. You have a 1/11 chance at the Hellforge Quest in NM, and again at the same quest in Hell.
If I wanted to run for a Lem, I'd likely pick the Countess in Hell. Other than the NM hellforge quest, there aren't really any good places to hunt for one before the Countess.