Soloman, to answer your points:
1. Go to the Scirra front page, click on "Learn More" then scroll down to Multiplatform Export where you will learn of the nw.js export for desktop. After reading this you would have to search google to learn about it if you were not familiar. You could also read some of Ashley's blogs like this blog about export options.
Regarding your other point here, can you please explain what deals would be broken by such file sizes - you have not made this clear..? Just FYI, Elder Scroll Imperial Edition is >110Gb, so what upper limit are you referring to?
2. If you can preview in Chrome then you can see what a nw.js export will run like. I am not sure what your reference about piracy is for exactly - but you should not expect to get everything for nothing when Scirra are running a business.
3. Google search nw.js github, which should be a natural inquiry (see point 1). There is plenty of information on github. You are confused about file size and performance.
4. You clearly do not understand what nw.js is - c2 only exports html5 and that exported product can then be wrapped by nw.js to be played on desktop. All of the c2 games on Steam are wrapped using nw.js in that way, and in spite of your concerns I am not aware of any buyer being worried about download file size.
5. Yes, but c2 games cannot be played in a DVD player, so I presume you are considering selling DVDs with your game recorded inside. If so, they will still need to run on the operating system of choice - this is a html5 engine, remember, and all exported games need to be wrapped if they are not to run in a browser (see point 1). If you're concerned about your buyers running out of disk space then I think it's highly unlikely that a 100 Mb addition to any game will be of concern to someone with a 1Tb drive.
It is worth also considering that you could also publish for Windows 10 directly....