Will -sN -sX and -sF work against any host, or just Windows hosts?

-sN -sX and -sF scans will work against any host, but Windows computers do not respond correctly to them, so scanning a Windows machine with these scans results in all ports appearing closed. Scanning a *nix or other system should work just fine, though. As I said in the main tutorial, -sX -sF and -sN are commonly used to determine if you're scanning a Windows host or not, without using the -O fingerprinting option.

The Nmap manual page should help to determine which scans work alongside which options, and on which target systems they are most effective.