1) There's more than one way to cool a hot brake. While venting of your drums and/or rotors is a good idea the fan isn't one of the more practical!
2) Before starting any brake job your drums and rotors should be measured to ensure they are not worn beyond their acceptable limits.
3) Prior to drilling, each drum or rotor is marked with a certain pattern, depending upon its use, and then hand drilled. The hole size is also determined by use. The entire process takes nearly 30 minutes per rotor.
4) Before and after drilling.