As for tools, I'm mostly on Linux and I use Quanta Plus. I haven't tried it for visual design, I just like it for it's syntax highlighting and assisting with functions when working wth php/html. My own HTML and visual bits are very basic though. The more complicated bits (if any) are server side.

I've avoided JavaScript but have (again) been toying with using it for a WISIWIG editor. Aptana (which is cross platform) seems to be good for that. I have also found the DOM inspector (which you get by doing a custom install and enabling design tools) in Firefox useful. The Web Developer toolbar for the Mozilla based browsers can also come in very handy when playing with web pages.

Onto the wysiwig editor. I've been looking around but haven't quite found what I want. I like AreaEdit which can do more than shown in this "simple example" but the main js file is nearly 200K and thier are plugins on top of that. A lighter weight one is whizzywig which I might use but at the moment am having a go writing my own, using the whizzywig code as a "helper".

Not sure I will get there though. Apart from trying to learn a new language (OK a lot is similar enough to things I do sort of "know", I'm a bit put off by browser differences and possible compatibility issues...