Two mods use different versions of the same DLL. Which one do I use

you should choose High Performance NVIDIA processor, this is suitable with graphics device of your laptop VGA card. About integrated graphics, this software installed automatically by OS ( WIndows ) and not match driver for VGA graphics device. Don't forget to check on Device manager to ensure that graphics device driver installed correctly.

Yes, it's possible, although getting them all lined up correctly is tricky - if your rotation is off, one of them will dock and the other won't and things will wobble all over the place. I often use triple 1.25m docking ports for ship assembly in orbit.

I note that you can do this in the VAB, sort of; you can construct your ship like this:

|  |
|  |
V--V
X
^--^
|  |
|  |

where the ^ are upward-facing ports, the V are downward-facing ports, and the X is a connection between two of them. Only one set of ports will link up in the VAB, but if you load it onto the launchpad, it'll usually wobble briefly and then automatically dock the other port(s). This is particularly handy if you're designing something that you want to be able to launch in one piece, break apart in orbit, and connect back together later, but also want to use 2-, 3-, or 4-port connections.