I am looking for a latex plugin for Visual Studio 2010 (preferably free) .
Features it must have:
I do not think that there's anything that comes close to what you want to do. But as far as I know, you can - in principle - use Visual Studio with any programming language. If you have enough time to configure it properly.
You can create your own LaTeX-specific language service. Moreover, you would have to create own build rules.
But since I think that is too much work, I recommend TeXnicCenter, a freeware program that has syntax highlight, autocompletion and error handling. I'm not sure about code folding, but I think it does not have this.
Another freeware is LEd (LaTeX Editor), that should have all the features you like, but as far as I remember, I was not that happy with code completion.