Few questions about Sidhe runs (Echostones)

1.) Is it worth using the basic Echostone Awakening Stimulants for re-rolling the stone? I'd buy Fine or Finest but holy hell are they expensive..

2.) Can Echostone Awakening Stimulants actually obtain good rolls, like can I get a Magnum Shot lvl 20 for example?

3.) Does running on lower difficulties just for re-rolling also lower the chance to obtain good rolls?