Linux is not GPLv3 for a reason[1]. Not to mention it's only a kernel, not an entire OS. Basing your OS on a Linux kernel doesn't expose your other code to the GPL. Writing apps to run on a Linux system doesn't expose your code to the GPL.
The Minoca OS folks are asking for the community to contribute code to their OS that's licensed under GPLv3. GPLv3 supporters are necessarily a subset of open source supporters. I contend that the subset is small enough that a Minoca OS licensed under GPLv3 will continue to experience a lack of widespread circulation.
Yes.
So license doesn't seem to be a sufficient impediment if the functionality advantages are sufficient.
This meme "seems" right, but I see less evidence for it in the field.