The Intel Windows driver (lower photo in your post #15) has nothing to do with how many monitors you might be able to have, it only shows how many monitors are actually connected and detected. If you plug in multiple monitors, it should change to show more than one.
Note the lower photo in my post #10, for example. The lower left monitor is displaying Win8.1's multiple display configuration window, where I've arranged the four monitors into a 2x2 grid. Win7 is similar, whereby you can tell Windows how the monitors are oriented in relation to each other--above, below, to the left, to the right...
And, yes, once you open a program in a window, you can use your mouse to drag that window across to another screen.
The middle photo in your post #15 shows the motherboard has four SATA ports (the light orange ports), so it's not exactly ancient,
*** 2011****
but the top photo of the back panel indicates it is nevertheless relatively old. That's evidenced by the parallel printer port, the 9-pin serial port, and the PS2-style keyboard and mouse ports. Those haven't been included on computers for many years now.
The age of your computer leaves open the question as to whether the built-in graphics subsystem will support the 29KW600's resolution--specifically, the 2560 horizontal resolution. You may need to check the computer's full specs if you want to determine that.
**** right again, 1920 x 1080 is the highest option****
OTOH, the 29KW600 has only HDMI and DVI inputs, while your computer has only a 15-pin VGA output, so that's an obstacle you'll need to deal with.
***** right again, I did not think to look at that either ****
There are adapters that will deal with the mismatch, but that will only be a viable option if your graphics subsystem will support the 29KW's resolution. If it doesn't, don't bother trying to get the 29KW connected to the motherboard graphics. Use an add-in card instead.
An add-in card will bypass the above problems. Take a look at the specs on
this graphics card, for example. It has VGA, HDMI and DVI output ports, and will support monitors on all three at the same time. It supports resolutions up to 3840x2160 on the HDMI or DVI port, and up to 2048x1536 on the VGA port.
You'll need to plug the add-in card into the motherboard's PCI-E connector (the dark orange slot in the middle photo of post #15). Given the age of your computer, though, you'll need to check the specs to see which PCI-E version that slot supports. (The add-in card example in the previous paragraph is a PCI-E 2.0 card.)
If you decide to go with an add-in card (which I think is a good idea), you may want to start a new thread to attract opinions from other forum members. The add-in card I mentioned above is only an example, not necessarily the best option. Other people may have additional feedback you may want to consider.