When tethered to my desktop pc and my galaxy S3 is connected to my home wifi will I use my verizon data or will it continue to feed off of my home connection and not charge me
Kind of a strange situation, but I believe bjboucher to be correct. If using mobile hotspot, I know that it can only use mobile data, but I've never tried with a wired tether.
If you want to be completely sure, you could mobile data off on your phone and see if Internet still works on your PC...because then it would have to be using WIFI.