- Wheelies are not in the demo version, and none was shown in any of the trailers (though you can see bikes now do a short wheelie when using a mushroom, but it's just for the sake of the animation). They did not confirm if it would be present in the final version, but you can assume it won't be in.
- Yes, bikes now have access to super mini-turbos (orange sparks) too.
- We do not know anything about stats. Considering the two above points (no wheelie + SMTs for bikes), karts and bikes appear to be the same thing now, the only difference being cosmetic like you said. (Well, actually it's a bit easier to avoid items when the vehicle is not large so bikes still have that advantage over karts.)
No bike with the “inside”-type drift (like Bowser Bike / Mach Bike etc. in Mario Kart Wii) has been shown.