First things first, welcome to the forum.
I have seen (and attended) seminars by Stahls covering a lot of Heat Seal, but never the screen printed part.
That is really an aspect of flat stock printing that many shirt printers have adopted, though often with shirt presses rather than the clam shells or jiffy clamp and vacuum tables often used.
Rhinestone lessons and webinars are probably going to be easier to find as they are sort of an add-on profit center for the heat press folks, and they want to sell you the supplies.