A "smooth" shave with 0.0mm is not possible, so you don't see the hairline at all. But very short, approx. 0.5mm or similar.

you can, but i wouldn't recommend it. i've only ever had problems with the blade, which quickly became blunt and didn't cut properly, and then there was the battery, which gave out after a short time. i can highly recommend this one. BaByliss Hair Clipper E990E