Any good Arc or Ball Lightning builds for a Shadow?

Hey everyone
Recently rejoined the game and have been struggling to settle on a build I can be confident will continue to work in the end-game. Though I've tried many of the skills to some extent, Arc and Ball lightning (Arc in first place!) have just been the most satisfying for me and I'd love to see if there's a viable build that works around them.

Any build recommendations would be amazing! I've seen some on the Witch forum that seem strong... but don't touch the Shadow area and I'd really like to stick with Shadow if possible.

Even if you don't have a build, answers to a few questions might help!

-Am I ok sticking with Chaos Innoculation and Energy Shield purely for defense, or will I need an additional backup like Evasion or Leech?

-Am I better off wandering deep into Witch/Templar territory for Block/Life instead?

-Which support gems support Arc the best?

-Are there any unique items I should keep my eyes out for? Preferably cheap ones!

Thanks a bunch in advance. Loving the game and hoping some experience players can help out.