I think I am on to something. I am now writing my XeLaTeX document in Latexian which has command suggestion, syntax highlighting, tabs and parses the LaTeX/XeLaTeX document and gives you an outline which you can use to navigate your document. It also has a live preview, but I don’t use it since Latexian does not do biber (pun not intended).
For typesetting, I instead use TeXShop which I have configured to use an external editor, so the editor does not pop up. I just get the console and the PDF output windows.
Also, since I am using XeLaTeX and biber, UTF-8 is no problem at all!
filtered by fnurl 
I see how to use XeTeX in Latexian, but can you tell me how to use XeLaTeX? I get the sense that some LaTeX features are not included when use just use XeTeX. Is there a package you can use to get the full LaTeX environment? Thanks!
Using XeTeX gives you XeLaTeX as well. I’m not sure which features you are referring to when you say that XeTeX does not give you the full LaTeX stuff, but I do not use that many features.