I only test drove the car for a little while, so I cannot give you as much of a complete opinion as the owners on this thread. Anyways, here are my 2 cents:
1) This is true because Toyota has raised the car way too much. Combine high COG with soft suspension and you get body roll. I doubt that you could improve it using a sway bar in the rear because the rear is already a torsion beam suspension(the beam sorta acts like a sway bar). Maybe a bar in the front would help, but IMO the best results will be seen by lowering the car.
2) Yaris' steering is not hard at all, it is in fact pretty soft. However, Yaris has the slowest steering ratio of any PKDM car I've driven, and that is why it has unresponsive steering. Even corolla feels like it has a hydraulic rack after driving Yaris. Steering feel is also pretty nonexistent. I don't think that you will feel like you're not in control of the car, but I prefer a tighter steering rack with a bit more feel.
3) Seats are excellent, they are very soft, only issue is that they are not angled upwards and provide little thigh support if you're tall. No issues for short people though.
