Crossword puzzle clue "legislative impasse and what occurs at this puzzle's circles"

Legislative impasse ... and what occurs at this puzzle's circles?

Per this puzzle's opening Note, where all of the "trading" in this puzzle normally occurs?

Athletic infraction ... or what occurs at the beginning of this puzzle's four theme answers, both across and down

Chemical reaction phenomenon, and what occurs in four symmetrical pairs of long answers in this puzzle

Pocketful of coins, and what literally occurs in the circled letters in five puzzle answers

Circles rolling around other circles

Secret get-together, or what occurs literally in each of this puzzle's circled squares

Action short of a divorce ... or what occurs in six long answers in this puzzle?