A hole saw leaves a neater looking hole than one cut with a jig saw.
Once the pilot drill goes in, tip the drill slightly to start the hole. I'm
guessing you are talking about the hole for the pin style seat.
As for the switch box, mock one up using cardboard or heavy construction
paper. When it is done, fold it flat and trace it on a piece aluminum.
Cut out the aluminum, and bend to the shape of the switch box.
Hope this helps.....Jerry