These details accumulate in annoyance and stress and given the anxiety of the Ironman, will distract you from focusing your thoughts. Corollary to 1. I liked feeling at home in Penticton in 1994. It was one less anxiety on my mind. I knew the area, I knew the roads.
Familiarity is a great ally.
Training - There are millions of different ways I am sure. You will pay dearly for the wrong foods. A delicate balance. One wants to be as strong and as familiar with the distances as possible, but in order to do this, the tendency is to do too much. So, while long runs and rides are needed, try to minimize them to the bare minimum you will need.