Q. 1. When I do adoration of the Blessed Sacrament, I do so for 5 to 6 hours at a time. During that time, I get hungry. It is permitted to eat something during the adoration of the Blessed Sacrament, even a cookie to take away one's hunger?

A. 1. As it is not permitted to eat during Holy Mass, it is not permitted to eat something during Adoration of the Blessed Sacrament.

My recommendation is that you do not sign up for 5 to 6 hours at a time. While it is impressive to do so, it is unreasonable. I recommend that you do two Adoration sessions of 2-3 hours, taking a lunch/snack break in between in order to stop and eat outside the Church.