If you have 512 MB RAM, you probably don't need that much swap. I've probably only touched 12 MB of swap total as long as my computer has existed.

I keep my DocumentRoot(s) in /home/*/public_html/. Matter of preference. I'd rather not give unprivelidged users write permissions on any folder other than their home dir. So I'd go with a /boot, a /, and maybe a /home if even that. But it's all a matter of preference.