I used 32 bit, 16 bit may or may not work as well - you can try. Gamma 1.0 is applied when loading image into 3Ds Max.
I used RGB swapping as for all the maps I found or exported from Mudbox I had to do it - not sure if its Corona or export options related - but as far as I remember, it was Corona related - It had to be done to make vector map work correctly.
Using -1 in vector displacement is okay - no problem with reversing.
I do not use ZBrush so I can not advice options - though, The more resolution you output, the smoother displacement will be. In Corona you then need to decrease Displacement Screen Size (from default 2,0) to make displacement more precise.
Your displacement looks correct - I think you have it setup right - but your boundaries doesnt look right. You could probably increase resolution and there may be some boundary tiling option in ZBrush while exporting you need to turn off or something?
All in all you can experiment, thats the best way to go about it.