The official guide to what's "on-topic" is burred in the *confusing mess* SE calls the "help center" (sorry SE, I know you were trying, but the HC is so much worse than the FAQ ever was).

From http://serverfault.com/help/on-topic

>Server Fault is a site for system and network administrators needing expert answers related to managing computer systems in a [**professional capacity**](http://meta.serverfault.com/questions/4111/what-is-a-professional-capacity).
>
> If your question is about…
> 
> - Server and Workstation operating systems, hardware, and software.
> - Business/Enterprise grade virtualization
> - Enterprise storage, backup, and disaster recovery
> - Network routing, switches, and firewalls
> - Operations, maintenance, and monitoring
> 
> and it is not about…
> 
> - Anything in a home or development environment
> - Product, service, or learning material recommendations
> - Career, salary, personnel, employment, or formal education
> - Licensing, legal advice, and circumvention of security or policy
> - Unauthorized hacking, password cracking, or system misuse

But that topicality is defined only within our target audience, mainly that first line with a link to a lengthy discussion of what "professional capacity" means. To sum it up quickly, it is someone being paid to maintain these on-topic systems in a supportable manor with the intention of ongoing operations. 

----

Addressing some of your questions directly:

 - The Environmental variables thing is a novice question, better suited to [unix.SE](http://unix.stackexchange.com)
 - The FAT vs NTFS question shows absolutely no research on your part. A quick Google brings up the comparison that Hopeless linked to. There's a blue pane to the right when asking a question, trying to give advice like `Provide details. Share your research.`
 - While about a quarter of the site's Answers come form a core continent of highly competent people, the majority come from random people who wouldn't even be considered *regulars*. Put a touch of effort into it and you'll be really surprised at how quickly you can find a question you already know something about.