Don't be too disheartened - I was the same initially, but most of the clues are more straightforward than Shark often is. I have all but 2. But that's where I've hit a wall. The bottom row doesn't suggest anything, and the interpretation of "systematically extract[ing] one letter" is still opaque. Early days though.
I'm happy with all my entries (easier Shark than usual), and I can see one possible word in the all-but-one-mirror-image-letters which would lead to a curve which would be hard to trace unambigously. I've not cracked the systematics of extracting letters from the omitted words, or found any sensible way to fill the bottom line, so have extracted the cork from a bottle of Rioja instead. Tomorrow is another day.
I've got the right hand side of the grid completed and much of the south west so still a bit to go. Have yet to see what the extra words have in common but it's early days:-)
Grid filled, couple to fully parse to our satisfaction.
Curves completed. Got all the extracted words and the theme.
But.......no idea what these messages are yet.
That’ll be tomorrow’s task.