I just started this document as a place to record the little things I like to change in any editor... and what I change them to.
Yes.
Line endings (CR/LF), tabs, extra spaces (if available) should all have visible markers, especially when working in text documents like markdown and textile.
Dark with light text. Not a fan of Solarized Dark. Atom Dark is Ok, Visual Studio Code's Dark theme is pretty good. Base16 Tomorrow Dark included with Atom, or Tomorrow Night included with C9.io are my favorite right now. The redish-orange value types are very pleasing to the eye.