Questions for Self-Publishers

I had questions for those of you that are experienced in self publishing,

Did you choose to file for a Ficticious buisness name, or start a LLC?

What are the benefits of either FBN (Sole Proprietor) or LLC?

What did you publish on first Kindle or CreateSpace, or another platform and why?

Did you get your own ISBN, or barcode other than the free one provided. If so what are the benefits of doing that?

Thanks in advance for sharing any advice. I am new to self publishing, and would like some guidance so I can start finalizing some of the decisions that I need to make.