Not necessarily. Remember that anything that's on the AH is there because it has NOT sold
Vials/Feverbranch are something that took a huge hit in value over the last two months. I was selling them as a noob for 20k gold, and now I see them up for 300 plat fairly often.
Again, not necessarily. It depends on the weapon type. Good weapon types will sell fast, and bad weapon types will never sell. For example, I threw a +1 LUB greatsword up for 500p, and it sold in a few hours. Better than vendoring it, and someone got a decent zombie-whacker.example : I put down a few +1 lesser undead/reptilian bane items