Okay the reason that everything looks like an HTML page is because that IS an HTML page. Firefox is a web browser, not meant for use like konqueror/windows explorer on local directories. It gives you links to the files, not the files themselves. It takes a list of files/directories in the directory it's looking at and converts that to a static HTML page, which you cannot edit or manipulate. Konqueror is the KDE file browser, which is used for (you guessed it) files. It does a great job at that, and a kinda-sorta-okay job at web browsing. Firefox is MEANT for web browsing and only web browsing, and has NO file managing capabilities.
Basically, you can't get the same functionality from Firefox that exists in Konqueror.
As for typing in a URL in the address bar and getting Firefox, I'm not sure if that can be done (I don't use KDE/Konqueror). If so, it would likely be a setting in Konqueror itself. I'd check, but I don't have KDE on any of my systems.
I hope this at least clears some things up for ya.