IFMAR is 60mm unless it goes into the roofline then it's 50mm. Do yourself a favor and get a circle cutter to make the cuts. Much easier and no surprises at tech when they measure the diameter.
You can remove both front side windows and the entire rear window also. I usually do the sides and just make two larger circle cuts for the rear window. Helps keep the roof stiffer so it's less likely to collapase during pitstops when your pitman picks up the car.