"Also, will Emacs answer my needs for HTML, CSS, JavaScript, PHP, MySQL, Perl, and Python coding? Especially when, for example, HTML and CSS, or PHP and HTML are mixed in a file?"

My personal choice for Perl and MySQL has always been a free small editor called PFE and for CSS, PHP, HTML, XHTML, Javascript, ASP etc I find I never use anything other than Dreamweaver and now with AJAX extensions its a one stop shop.