Actually (before this reply was posted), I saw where someone had used Chinese KingRoot to root, and then used a shell script that would replace KingRoot files with SuperSU. Root process worked perfectly, and although the shell script displayed several errors, it did in fact install SuperSU, and root was still alive & well! The tethering fix would not work in my particular case (menu item never displayed -- I rebooted and checked APN settings and my mod was still present). Ended up buying WiFi Tether Router and it works perfectly (well worth the $2.80 in my opinion -- FoxFi and the most others simply would not work).
Thanks everyone for your kind assistance! I now have a free 1GB/month LTE "hotspot" which required a very minimal one-time investment ($39.99 phone, $12.88 RingPlus activation for their free 1000 minute, 1000 text, 1gb LTE data plan, & a $2.80 phone app for tethering). And I can always use it as a backup "phone" if something ever happens to my Galaxy S3. Not a bad deal at all (IMHO)...