Custom weapon drops and vaporization

I have two questions that are totally unrelated, but i will ask them both to save topics

  1. How can I disable the default dropping of weapons by NPC’s in a way that will allow me to make them drop my own entities later?

  2. How can i make a person or npc instantly vaporize as if they had been hit with a combine ball. I want to have the suicide on my server be that instead of just killing the person.