Yup, just scribe the hole marks by holding the fan in place and making the spots where the holes line up making sure the fan won't interfere with the plastic clips that hold on the bezel . Drill away. Completely cutting out the grill will yield less noise and better flow although the square holes in that case are nice and free-flowing. For the screws, just take the fan to the hardware store and find sheet-metal screws that a just larger than the fan mounting holes. That'll hold the fan in place nicely for about $0.05 a screw.
There might be a notch cut out of the bezel on the bottom which allows the air to enter. Modding the case with a 120 will increase the airflow so make sure the bezel-hole is large enough to feed that air and make sure you don't have the case sitting on a carpet or anything that will plug it up.