The entry for 41, assuming you have it, is the definition for 40. It's not a word; it's a series of 41. The English word for this series is the translation of the location of the event.
The starred cells are the answer to the clue given by the extra letters in the down cell. An easier way to think of it is: it's the description of the event, 5 letters, the last two replacing the letter in the final cell using the system named in the circled cells.
I hope that makes sense.
8d is actually a double definition for words with the same meaning. The first 4 words including the extra letter in the 4th word are the main definition. Adding the last 4 words (ie the whole clue) provides the other definition.
20d The definition is the last 3 words with an extra letter in the 2nd of those words. The wordplay is the first 3 words with 'bar' in the sense of 'except'.