I've been writing on the Mac for a number of years now. Over that time, I've settled into using Scrivener for project organization, version control, and major publishing; and Sublime Text 2 + Markdown Editing for Sublime Text 2 for most of the actual writing. I use Marked for the publishing right now (I mostly blog at Wordpress, and this workflow lets me quickly build reasonably complex blog posts).
Unless you're technically-inclined, I'd recommend just using Scrivener. See this introductory video for a good overview. At its core, Scrivener lets you break up big projects into small chunks, organize them in whatever way suits you, and then get writing.
It's also got powerful version control (I recommend using the Snapshots feature liberally), an attractive full-screen writing mode, and excellent publishing support (output to .doc, .pdf, ebook formats, .txt, MultiMarkdown, and god knows what else). My favorite feature is that Scrivener allows you to bring your research materials directly into the project file, for easy access later. Very useful for term papers.
It uses the standard Mac text-handling engine. If OS X supports the languages you mention, I think Scrivener should too. If in doubt, try the free demo.
The learning curve can be somewhat steep. It's worth it, however, if you're managing a large writing project with a complex structure or one with lots of background information.
If you don't intend to do too much writing, or only write simple projects, you might be better off sticking with Word, Pages, or even just TextEdit at the start. The tool is just that, a tool. If it's getting in the way of your writing, then go back to a simpler tool.