I used to work as a Barista.
I don't think I could ever be a barista and make all those different espresso-based drinks.
Yea it is a lot of memorization of adding different ingredients.
Although it may be relaxing to work in a coffeehouse where they serve hot coffee, tea, and sometimes food.
Yea there are lots of time for relaxing when you are not dealing with customers.
Actually all coffees are based on either espresso or coffee. There are different strengths and some have milk or cream and some don't. 
That is true, do you like cofee? You seem to know a lot about it.
I like iced coffee that is brewed cold and has different flavors.