Since BBEdit is 'just' a text processor, the easiest way to put a link in is to just type the HTML code for the link in. Since you added the link to go to blah link to your post, I'm assuming you know that much HTML code, so it should work fine.
Don't know about WYWIWYG editors, though - personally, I've never liked them. I've been coding my site with BBEdit, Pepper (another OS X text editor), or vi ('cause I'm a glutton for punishment) long enough that I've never liked any WYSIWYG editor I've played with.
For pages under URLs such as http://yourip/animals/ or http://yourip/cars/ and such, those would just be subdirectories within...well...
(My apologies if I'm jumping ahead in the lessons here...)
As morbus said, the url http://yourip/~yourname/ points to your /Users/yourname/sites/ directory. However, the base url http://yourip/ points to the /Library/WebServer/Documents/ directory. Creating a subdirectory called 'cars' in there would give a system path of /Library/WebServer/Documents/cars/ that would be accessible from the outside as http://yourip/cars/ and would display whatever was inside the 'cars' directory. That's the easiest way that I can think of. The user (Joe, in your example) would still have to navigate to that folder rather than having it residing in his home directory...but if you really wanted to then, I suppose some creative aliasing could take care of that.