I enjoyed solving the clues, and, as the theme is something dear to my heart, I was able to guess the entries (and then verify them later).
I don't have a problem with the wordplay to the 8th Across clue.
What I am struggling with is the concept of Grid Entry Order. I know it is not the order of the solutions which are, of course, in alphabetical order. I also understand that we are to ignore the thematic entries. If I focus on the other Across clues, I get something which makes sense. However, what do I do about the Down clues? If I take these in the order they would appear in a crossword, I don't obtain anything sensible. Perhaps I should be scanning the columns?
I will try googling to see if GEO is a standard term.