1. No, you don't *need* to have a tail. They're quite popular, but you can take them or leave them. You can even make as many furry characters without tail as you want. 'Twould be an interesting change of pace, if you ask me.
2. It's not a term specific to the fandom. And unfortunately, it only belongs to the "adult" side of things. *sigh*
3. Well, err... Have fun? That's honestly the only thing I expected from the fandom before I entered. Oh, and be mindful when you're looking around on internet. Like with everything, there are some... strange... sites and articles related to the furry fandom.
4. I have four characters so far. One of them, my main fursona, is a feral that can talk. My latest character, however, is an anthro that doesn't talk (but still understands language just fine). As for people in fursuit, well, that's a whole other story entirely.