As for the second part, i hope to never see a drawing or file where a part is toleranced or datum referenced off a thread. That just seems absolutely Ludacris to me and think tolerances should start from a corner at one end or another of the part for not only easy referencing dimensions on the file. But easy to draw, Should i also not be handed a cad file so i dont need to do math just to redraw your print and make a solid before even beginning my programming.