HTML can be used without CSS, however, most of the tags used in older versions of HTML to position and style pages are now depreciated by the W3C. Use the current HTML5 and CSS3; they have some great new features.
Fluent in what? There are dozens of popular scripting and programming languages. Insisting that you're fluent in "coding" gives the impression that you have absolutely no idea what you're talking about. You made no mention of a specific use for "coding". People can't read your mind. Be more specific next time.
Everything about HTML and CSS's use on dA can be found via Help & FAQ: [link]
No, they usually don't. Firefox and chrome are free to download, there's no excuse for anyone to be using IE or any such crap. If people use non-standards-compliant browsers, they can only blame themselves.
Really when you get down to it they're both languages. HTML is a development language and CSS is a styling language.
If you think of it like a gift box you get a present in...HTML is the gift box itself and CSS is the wrapping paper on it that makes it look pretty.
Limitations are really based on current internet browsers and what CSS can and can't do. It really depends on what you want to do with your HTML. Do you just want it to look good (meaning not plain text on a white background)? Then you just need CSS. Do you want it to have advanced functionality? Like if you click a button something happens. Then you're looking to add a scripting language like php or jQuery for example.
Basically you can look at it this way:
HTML = the bones CSS = the skin Scripting languages (php for example) = the organs/muscles
Used all together and you get a dynamic website vs a static one (just HTML & CSS).
Yeah. I know all that, I've been coding for a long time (everyone thinks that just because I asked I don't know). I was just wondering if they'd let you use CSS or if you had to struggle along with HTML. I know its 'essential', but I just think it's boring. CSS was a lot more fun when I learned it. And since I'm lazy, I don't want to have to work all the CSS out to come to find it's non-applicable. Also, thank you very much for not belittling me like some other people have.