DHEA does not convert primarily to testosterone in males, but remarkably well in females.
Any increase in testosterone by DHEA will also aromatize to estrogen in most cases- this is where dosage plays a huge part as you mentioned.
Well, yes— and no. The biochemistry is complex, and genetic mapped triggering (ie. more effective in some depending on the gene region confirmed— a lot to this). All per oral pro drugs and/or hormones are converted by the pH2 stomach acid, so there is that also on the dosing. My message was— any “clinic” that hypes high expense per oral anabolics (which, even if true would be illegal without prescription) is ignoring the rather prominent effect of denaturing protein/hormone in the stomach. In short— they must be injected- and thereby creating another level of risk. See: bodybuilders (the old joke was— build muscle, shrink the “tower of power and the gonads” for really silly reasons.