What prizes were won if the star was hit on the first turn; just the ones already revealed?
That's a good question, and I assume now that was part of the point of staking the game with headstart prizes (the other part being to speed up the game). I only saw portions of Banko, so I don't remember some of the finer details you're after. But your guesses make sense.
Could you clarify what "the used squares didn't go out of the shuffle" meant?
Whereas in the front game you couldn't hit a revealed square again, the bonus light traveled across all the squares - blank or not. Thus, the Thing To Avoid in this bonus game was a blank square.
One neat bit of strategy was the square that gave your opponent a free turn. You (as the spinner) chose when they took it. Ergo, if you had 3 spins left, and Banko wasn't possible with just 1 spin, it would be wise to let the opponent take their free turn before you finished your 3.
-Jason