I've done both. for the stickers just park in the sun and it will come right off using a fingernail. then use some wd40 or tri-flo for any left over sticky. The mirror tap is to let the water drain after washing so you don't get constant dribble out of it. Use a small bit first then if you feel you need more just increase the size.
If you have had the stickers on long. Some auto polish will do wonders and clear any remaining residue that won't be seen until under certain circumstances...i.e. water(rain), certain sunlight...blah blah.
__________________ 2007 JK 2-dr X | Steel Blue | 4.10 Auto D44
The holes are drilled to allow the water to completely drain, from the mirrors, especially when you are washing your Jeep. The soapy water has a chance to drain, without pooling and causing soap streaks on the door.
I have done this project, for both of our Jeeps, and, no matter if we hand wash, auto wash, or wand wash our Jeeps, there are no soapy streaks on our doors.
Just make sure that you take the mirrors off, unless you feel confident in your drilling with them on.
Most parts stores sell a rubber wheel that connects to a drill, it took me 5 minutes to remove the "X" on both sides and it won't stripp the paint as long as you keep it moving. Been using these "eraser wheels" for years now.