Some Questions about Amara

Hello there,
like mentioned above, I have some questions about some interactions of Amaras different skilltrees.

  1. I’m using Ties That Bind as AS. Will the shared damage from TTB heal me, if I’m using Soul Sap on it?
  2. Sustainment says, that elemental damage dealt by my weapons heals me. Is that also true for the chainlightnings from a Brainstormer?
  3. I’ve read, that TTB procs Laid Bare on chained enemys. So, why does it not trigger Samsara stacks?
  4. I’m looking for a good elemental weapon for big bosses. Brainstormer is planned to be my main weapon for mobbing, but I need a good weapon for huge single target elemental damage to melt bosses. Any recommendations?
    Hope some of you can help me out.