What about flyweight? do you think I should get one (to play Arkanoid first)?
Not really; arkanoid was a geared spinner, and while the weight in the flyweight will help with the initial feel of a not moving spinner, it will also spin longer, which arkanoid's gears worked against.
On the TT2, is the "energy cylinder" essentially a flyweight with a different name? 
Yes
Note that all three knobs should be interchangable between the models, so if you don't mind the extra shipping, or buy from a reseller that stocks both, you can mix and match. The two knobs that are special designed for a specific spinner AFAIK are the TT2's steering wheels and the TokenTop™, so I don't know it they'll work on other spinners.
I have the SpinTrak and TT2 and other older spinners, but not the tornado. The tornado was better than most other spinners when it first came out, but now its lower res is hurting it, especially with arkanoid. Otherwise it's still a good spinner.
That said, I like both the SpinTrak and the TT2. Both are high res (1000 cpr & 1200 cpr, respectively), and sturdy. I do like the TT2's button-like mounting for it's simplicity, but am not sure if it makes the knob (that I have) look too far off the CP. (I'm actually surprised it bugs me so, as the difference is almost not noticeable.

) Since I don't have the wheel, I don't know how it feels, but others here love it. The SpinTrak doesn't have the, errr, "flash" of the TT2, but it just works great. The spin res difference between TT2 and ST is noticeable side by side, but almost feel the same when either are compared with my older lower res spinners (ie, both are way better res than my 24-72 cpr spinners).
Some people are able to play arkanoid with low res spinners, but I can feel the difference on my lower res spinner even after adjusting the mouse sensitivity. The paddle seems to jump ro skip more rather than smoothly sliding, and it's missing ... something that playing with the TT2 & ST has. Responsiveness? Speed? Lag? Not that I can see, but maybe a combo of them?

I can play "fine" with the low res spinners, but not as great as with either the high res spinners. (Still not as good as I was as a kid in the arcades though; maybe if I played as much....

)