Any American students attended the Edinburgh Festival in a prior year?

My son is performing at the Edinburgh Festival at the end of August. Have you been during a prior year? How much money did you need for ten days for lunches and souvenirs? Did you exchange before you went? He will be in London for 2 days, and from what I understand they use pounds where Scotland uses the Euro. Was it easy to change over the money once in Scotland? Did you use a debit card? What was the environment like during that time? Is it easy for 17 year olds to obtain liquor?