I've read through the documentation and forums, and tried various settings with
no luck.

What I need is a copy of a website with relative internal links and absolute
external links, including absolute external links to images.

Here's what I am trying to do:

Create a copy of our old website.

Upload it to a directory named "archive" on the new website.

When a visitor goes to the archive directory, I want the visitor to see the
old site and be able to navigate it exactly as before it was archived.

I understand that the url's will be different when navigating the site.

HERE'S the problem: I don't want to download content from other websites. I
want the url's that link to other websites to still go to the other websites.
I want images linked from other websites to display the image from the other
site, not copy it.

In my mind, that means relative internal links and absolute external links.

What's happening is: 

Images, pdf's, and other files that reside on external websites are being
mirrored instead of linked.

The links to external webpages are absolute (which is correct), but WHttrack
displays a warning that the link goes offsite. I don't want the warning. When
someone clicks an external link, I want it to simply go there.

Also, if possible, I want all links to external websites to open in a separate
browser window (target= "_blank")

I must be really dense, because this seems to be a pretty obvious use, yet I
can't figure it out and keep getting all of these images, really large mp3's
etc., copied to my mirror.

Any guidance would be greatly appreciately!

Geoff