Sorry, I did not yet went through this so I'm of not much help at this point. I would not suggest to use 3,3V adapter on 1,8V device - at least not before you heard of positive experiences with doing this. The risk of permanent damage always is on the side of the device with the lower voltage. In the worst case, you must build a level converter.
For the layout, have a look at these threads:
https://www.mobileread.com/forums/showthread.php?t=96442
https://www.mobileread.com/forums/showthread.php?t=99177