Enjoy the good coffee while it's there. Here stuff is usually good in newly opened places or if it's a new product, but later gets worse. I don't drink coffee, but I worked at a cafe for a few months. The suppliers are like drug dealers. They bring you the good stuff a few times, then switch to worse, but with the same label. Some would offer the old stuff, but as a new and more expensive type of coffee.

The park is called "Градска(та) градина". :) I guess it's "(the) City Park" in English. It's the oldest park in Sofia, created in 1872. But a lot of people refer to it just as "the park in front of the National Theater".
And I don't know if this would be interesting to you, but if you take interest in Sofia, it probably will be. It's a site with old photos and maps of the city, some from more than a 100 years ago, compared with recent shots - http://www.stara-sofia.com/