The part1 described some troubles with the screen sizes of the mobile devices. Since then I spend some time playing around with the problem and I found 2 wrong solutions until I got the (hopefully) right one. So let's start with the first of the wrong ones.
The solution relies on the fact that we have the device screen width and height in our DMS (Device-Management-System) database and this is compared with the real width of the device using JavaScript, then if there is a difference a cookie is set and via this cookie our Renedering-Engine on the web server is instructed to resize the images using the zoom level. It requires refresh, lot of "junk" in the HTML header and all the "machinery" on the server side. But the images are properly fit even for Opera browser that has the same user-agent string for different devices with different screen sizes.
See the code below, it's a nice example of a working-complex-bad solution :-)