Re: Stoning the pillars/walls at Hajj.
let me address to your point number 2 first.
No one is saying that people should go to get died over there. Every possible things need to be done to make sure that such a tragedy does not occur. The point was that in case of accident where such a tragedy does happen, take it as the will of Allah and understand that whoever died, died one of the best death one can have.
Now coming to your point number 1:
shaitan thingie?
well… those are the three symbolic places where Iblees met Syedena Ibraheem:as: first as a child, then as a yongster and then as a grown up man (some narrations also tell us that eventually he came in the face of a big bull) so that he could stop Ibraheem:as: from sacrificing Syedana Ismail:as: and at that time Ibraheem:as: threw pebbles onto him and he disappered. So really it is part of hajj as a Sunnah of Ibraheem:as: made compulsory just like sacrificing of an animal made compulsory.
It’s a metaphor to reflect upon a great event of history. Throwing of pebbles is a part of hajj and not performing it nullifies one’s Hajj altogehter. It symbolizes the power of a human to threw away his or her wishes for the sake of Allah.
The soul of the whole Fard of Hajj revolves around these “Manasik” termed as Fard by Prophet:saw: himself.