1. A visitor must download and save your source code on their computer in order to view your web page. If they don't have the source code, they don't see the site. Same goes for images. It's as simple as that.
3. There is some webservice called copyguard (or something like that) that takes your source code and compares it to the rest of the web on a regular basis, and alerts you if it finds a copy on someone else's site. That still doesn't solve anything unless you're willing to take legal action, however. And I don't know how much it costs. On top of it all, what's to stop someone from copying your source code, buying this service, and then accusing you of stealing from them? I can't imagine it would hold up in court.
4. Speaking of going to court (and no offense intended), your (or anyone's) source code is probably not worth protecting anyway. I'm not getting into the whole "philosophy of open sharing of information that the internet is based on" issue; html is just html. You may have some awesome server-side crap developed that's worth holding on to, but it outputs normal html and can't easily be "stolen" anyway (if your server is set up properly, that is).
Edit: for the benefit of the readers, I'm pulling some of the good responses from below into this post.
Originally Posted by djr33
Originally Posted by jscheuer1
Originally Posted by forum_amnesiac