Here I am, my GS300h is a Premier model with 19" rims.
1: Even with low profile tyres ride is good, it gets firmer in SPORT+ mode where dampers are set for best sport performance and steering is harder too; in SPORT mode (not +) you have only a better throttle response.
2: Yes, but don' t expect the power of a 450h with 120 HP more.
3: Yes, but not the way reviews talk about: it is the different way how hybrid eCVT works, with engine at high steady revs till you ask all the power, and low noise and revs when you need no more. GS is one of the best silenced car you can choose.
4: more than you can imagine, I wrote much about this, imagine to have same mpg of a similar diesel car or better.
5: Good colour combo, my GS has more classic colours, dark grey and tobacco interiors, but for a F Sport version your choice is sportier.