Are there any decent options on Linux for developing Flash or HTML5 applications, along the lines of Adobe CS or Edge?

Alternatively, how important is an IDE for these things? I've never done either before (have done: HTML, CSS, JavaScript, some Java, Perl, C). Can Flash or HTML5 applications be created with text editors alone?

Thanks.

HTML5 can be created with text editors alone. It's not too bad, actually. Tools like XAMPP can get you a good LAMP style stack that's very simple to manage and test.

I do a great deal of work in Perl, CSS and Javascript, almost exclusively in Vim. It's certainly possible, though some people might prefer to have an IDE or something. A matter of preference and taste really. Vim can easily be configured to auto-indent, fold up subroutines, and it will handle the syntax highlighting by default.

I can't speak to Flash development, since I've never done that on any platform.