loren3, to answer your questions:
a) It's possible. Probably the quickest way to do so is to go into your httpd.conf file, search for "/Library/Webserver/Documents" and replace it with the full path to your user directory. When you see a line that says something like "<Directory /Library/Webserver/Documents>", then that's the place you want to change. Messing around with the httpd.conf is touched upon in later parts of this series.
b) Possible, but will not be touched upon in this series of articles. Generically speaking, the "~" is special in the sense that it denotes a username - if you really wanted "animals" and "cars" owned by separate users, then you should just do http://myip/animals/ and http://myip/cars/. That's left for you to figure out though.
As for WYSIWIGs, dunno, never used them. As for BBEdit, this is the wrong place to ask ;) ...