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.