Yep - Firefox is the preferred browser here, but my web design part of life means that the IE6, 7 (& now 8) crowd must be attended to (& the CSS, etc. dings), so I havent gotten into the habit of Firebug.
Just don't think of it really . . .
Which leads to your excellent observation (twice) that the .js script "was not found on this server". Because of the multiple levels of security (whatever) on the various web hosts that my clients use, the "local" setup that is in use here means that "WA_eCart" was set up in a higher-level directory. As the resident idiot, I assumed that a simple "../" prefix would point everyone & everything in the right direction . . .
I have now re-positioned "WA_eCart" (plus pointers) and the copyShipping.js file works a treat on the "CustomerInfo" page - but the billing/shipping info still does not transfer to the "Checkout" page . . .
But, energy has returned!