How does "lo takifu" mean "do not round?" I would have thought that it would mean "do not surround." Are there any commentators that explain this word? If so, what do they state? A second question is: Why are we stringent with cutting pe’at harosh, making sure not to cut it too short? What is the reason that cutting pe’at harosh hair short is a problem, even if you can grasp the hairs with your fingernails?

"lehakif" can mean both go around and surround. Since the command "lo takifu peat roshechem is juxtaposed with "v'lo tashchit et peat zekanecha" (Vaykra 19;27) and the latter refers to cutting the beard it makes sense that the former prohibits cutting the corners of the hairline to create a straight round line i.e. without the peot.