First Layer Calibration / Benchy Bottom  

Looks good

Posted by: @yangorang

So I seem to see some different instructions for how to go about doing this - some say to just bring the nozzle closer to the bed until you can no longer fling the filament off by brushing your finger across it, others say that the benchy bottom lines should just barely be merged and you shouldn't see any gaps.  So is my -0.82 pretty spot on?

It looks good. The downside to going too low (too negative) is that you can start to get elephant's foot. It's always hard to tell from pics, but be sure you're not getting a bit of lifting along the edges.

First Layer Calibration / Benchy Bottom

Right so if I've got an elephants foot and curling edges then I've probably gone too close.  Right now the transition from the first layer to the rest of the hull looks pretty good, so I think I have things dialed in decently well.

First Layer

Is it normal for PLA prints to leave a clear outline on the PEI smooth sheet when detached or is that a sign that the first layer is set too low?

Sound normal provided the PEI is not damaged

Posted by: @yangorang

Is it normal for PLA prints to leave a clear outline on the PEI smooth sheet when detached or is that a sign that the first layer is set too low?

A bit of "ghost" is normal. It shouldn't be pressed deeply into the PEI. Give it a good hot rinse and maybe a very gentle application of a kitchen sponge and see if it comes out. I find a bit of acetone often gets the last filament remnants off the smooth PLA, although this is no longer recommended by Prusa. Over-used, it can make the PEI brittle.