PLA or anything hard (but people are using PETG as well)
layers:
a lot of people just use 0.2mm and are happy with it
but you can use variable layer height for finer results (down to 0.07mm where needed -bottom and top part) → see 3mf/gcode example
TIP: use skirt of 1 layer height for immediate test :)
❗ How to remove it from the plate after printing:
metal removable plate:
just take the plate away from printer and bend it - model will be removed by itself
glass plate (non removable):
well you may have little problem, people are solving it by putting some tool in the hole in the print (like a wrench) and by some force they pull it off
Inspiration:
i was using for a long time this rounded scraper from BaGoon
I was happy with it, because given shape is by far the best for removing any thin layer of printed object
BUT it was uncomfortable to hold it, sometimes even painful (too small sharp holds)