I don't know where to download hatch patterns (StoneCAD or other free hatch patterns). I am in the Tools, Options, File, Support File Search Path, but not sure what to do in there.

It's a lots of wayy where you can hatch patterns. I reccomend ask Google.
Tools for creating hatch patterns: HGEN, AHatch Pro....

tool to draw custom hatch and some 40 hatches ready to use:http://www.abcautocad.it/software_autocad.html

You are able to download hatch patterns from www.revitcity.com free

Sorry, are you asking about downloading hatch patterns, or how to get them "into" AutoCAD?It sounds like you're asking the latter..  You need to backup acadiso.pat and acad.pat files (just in case!), then append the hatch patterns to both those files (although usually it's acadiso.pat that is used) - there's a section at the end which indicates that it is for user defined patterns..  Then in AutoCAD they should appear when selecting a hatch pattern (after starting AutoCAD anew) - then they should appear at the end of the list..HTH:)