How is my 960 site filling a 2000+ pixel tablet screen and scaling down for a phone?
This is a site that was created for me and I can't make head or tail of the source code. On a simple brochure site I created, I did it all in percentages, so it's clear to me how that works, but is it possible for a fixed width site where pixels are absolute numbers rather than percentages to scale up and down this way?
Phones/tablets by default will zoom out a layout that doesn't fit, this is so that they work with all the existing sites out there that don't design specifically for them.
If you do want to design specifically for small size screens you can disable this feature which will prevent the zoom using the viewport meta tag.
Which tablet is bigger that 2000px ?
If you mean the retina iPad screens they still render at 1024px in css, they just squeeze 4 physical pixels into each.
I'm interested to know how it works now and how it will work about a responsive update.
I think you have your answer. A fixed width design will ted to fill the screen, normally ... but if it doesn't, you can force it to with the meta elements Mark referred to. If you set, say, a % width on a wrapper element, that element will fill that % width of the screen.