Hi guys, been wandering about in the last hour or so, and a few questions have arisen. I also use this topic to present myself and say "Hi".
Welcome - good to see new people taking an interest.
So, as far as I can gather, SGDK2 is stable, but better than that is the possibility of exporting to .exe or HTML5. What about other OS's? What if I want to build on Linux? How hard is it to set up? I intend to make games available to Windows and Linux (Mac is third, but I don't have one).
There is some support for Linux. I once managed to create a project which could compile and run in Linux. The IDE doesn't work well in Linux, but the generated projects can run in Linux with the help of the Linux template (separate download). At least they could at one time. I must confess I have not done much testing or ongoing support for Linux, but am willing to offer some assistance to the extent I am able if you encounter troubles trying to compile a project for Linux. The alternative, of course, is to simply target HTML5, which would work on all platforms.
Also, am I allowed to distribute my games without restrictions? I read the licensing post here, but the post only relates to projects hosted on the website, am I safe to assume that?
Yes, you can distribute your games wherever you like.
Considering the 2D nature of SGDK2, can anyone shed some info on how it performs in a virtual Machine environment to test?
I don't recall having tested performance in a virtual environment. The biggest factor there is probably the use of OpenGL. If you can play other OpenGL games in a virtual environment, I would expect performance would be similar. Of course you could test it easily by running the sample game in a virtual environment. I expect performance would be good.
The C# present is pure C#, right? No adaptions were made, like most engines, where JavaScript becomes UnityScript in Unity or UnrealScript in UDK? I want to use this as a means to improve upon my C# skills, and use the game-making motivator as a learning objective makes things better. Having a book abut C# near is always nice, and using references that can be used directly in our creation is cool. Not quite so with other editors.
The SGDK2 IDE itself and the games it creates are all 100% C# code (unless you export to HTML5 in which case the game becomes JavaScript, which is remarkably similar). However, when you are using the rule editors to define how sprites and "plans" operate, you are working one step up, simply calling C# functions with very little need for C#-specific syntax. That's why the games can be exported to either C# or JavaScript (HTML5) format if you are only using the rule editors. The real C# work comes in when you edit code in the SourceCode node of the IDE. Of course, there is the SGDK2 framework which offers some functions that you can call that would not be there if you were writing C# code without those functions in your project. But yes, the C# code
is pure C# with no extensions or modifications.
In fact the C# is so pure that when SGDK2 compiles a project, it also generates a .csproj file that you can load into Microsoft's Visual C# Express IDE and edit, compile, test, and run your project as a pure C# project.
Are any help files online? From the machine I am right now, I can't read the help files because it says that the navigation is cancelled (work computer), so all literature is out of my reach until I get home. 
In order to unblock this, see
http://gamedev.enigmadream.com/index.php?topic=1400.0. I could post the help files online, but I have not done that lately. The last place I posted them was at
http://sgdk2.sourceforge.net/Documentation/Index.html, but those have not been updated since version 2.1.6. If you have trouble accessing the help file still, let me know and I can update the web-hosted help pages so you could look at those instead, and see updated help content. The delivered help file is much nicer, though. For one thing, it will jump directly to the help page for the screen you are looking at in SGDK2.
