I am going to do this with my pear tomatoes, roma tomatoes and Cherry tomatoes. I haven't been interested in spending the $10 a topsy turvy and the logic is adequate on her proposal.

Though, with the tying of the strings, I would loop one string through two holes(across from each other) then on the other half of the bottle, string another equal lengthed string through those two opposing holes. It will balance better if its windy and it seems like it will be stronger then the simple knot she uses to combo those 3 cut strings.

Just a suggestion.

Marigolds are good for on top of the plant...
But, I would recommend oregano, basil, thyme, to complement flavor and add to the edible gardening factor.
If you want flowers, nasturiums are fully edible flowers, and colorful and would grow nicely.