Upload & Sell: On
Ben - What you're saying makes sense. Perceptual automatically does the black point compensation while Relative you have to actually make the choice. Just to be clear, what that does when checked is to move the 0,0,0 black point (if you had that) in the source file to the point in the paper profile below which you lose all detail. So, a 0,0,0 black in your RGB working space might become, for instance, 0,11,11 for Hahn308 on my Epson 9900 using Relative. That's why checking BPC make the preview go lighter - it's actually moving the numbers up the scale.
The paper white simulation is the hardest to get right in the profile. How accurate it is depends on the profile software and, more importantly, the quality of the spectrophotometer, and because we humans are much much more sensitive to the slightest change in white illumination and color of white, it's very hard for consumer level instruments to be accurate enough. Black point simulation is not usually an issue as there have to be relatively major color shifts just for us to notice.
Hang in there. You'll get the hang of it and you will enjoy it. You just need to understand there is never a one paper fits every image approach that will make you happy.