Its a good skiller, I would murder you for some 99's like those, I wish I still had time to no-life on Rs. They got the slayer through the methods mention above, but good fine none the less.
Some quests do, some dont. Most skillers use Lamps, Books, etc. I was at GE once stat spying people, a level 3 Mod Came, she had almost around 5-7 99s and somewhere around 67 slayer.