I am thinking that a game of Arkanoid could be fun.
A quick poll, for those of you who own one of these:
1 Does it matter whether I buy the SpinTrak or the TurboTwist?
Not very much.
Biggest difference is how they are mounted; four point screw on + 1/4" center hole vs single button size hole. 1000 vs 1200 cpr is a small difference, since both are greater than the original.
They can swap knobs, so that's not an issue IMO.

Buy both

2 Do I need a flyweight?
Not for arkanoid (the original controller use gears that slowed it down. Tempest, OTOH, had a flywheel. If you get one of the heavier knobs, it's a good compromise.
3 If I also want to play Discs of Tron, do I then need the Blackhawk push/pull spinner?
4 Is that spinner worse than the other two when playing Arkanoid?
5 It's been said here before that the Tornado spinner is useless for Arkanoid. Is that so?
Yes,
Yes, and
Useless might be a little strong (although others will same yes). How about "Not as nearly as good as the original, or SpinTrak or TurboTwist2"