1. To understand Clojure stacktraces you should read https://8thlight.com/blog/connor-mendenhall/2014/09/12/cloju.... Although I agree the lengthy huge Java dump when crashing is pretty awful, you can ignore most of it.
3. I would recommend you look into Parinfer - https://shaunlebron.github.io/parinfer/. You can manage scopes with levels of indentation, rather than having to move parens around. It works with most major editors, including Emacs.
But the Neovim port is great. Installation requires a little patience, but it works well.
In any case, one should read the Clojure style guide on GitHub [0] and get used to writing code in normal editing modes first. Then move on to Parinfer or Paredit once you feel the shape of the code and sense why it's like that.