There's a 30 pages discussion on ACC forum about kerbs, developers recognized there's something wrong in tire physics when hitting a kerb, they released a first fix in v1.02 (if I remember good) that makes things way better and said the job will be completed in further releases. ACC is still in beta... Concerning R3E, I wait with impatience every new physics update from Alex, it makes this game better every time.
Physics updates always entail the whole class. It wouldn't be fair to just update a few of them, not to mention that BOP would become even more of a nightmare than it already is.
I'm pretty sure they are. After all many people own and use them, and you can actually still purchase that particular one. But only @Alex Hodgkinson can tell for sure.
I think that if people start talking about which sim is most realistic, then it is time to turn FFB off and start doing some controlled tests, like braking, accelerating, skidpan, pushing car out of control with controlled and repeatable way. Car setups, resulting alignment and changes in roll centers, camber etc. are then something that needs analyzing. FFB has nothing to do with how realistic car drive, it has to do how nice game feels for personal liking and that is where most people commenting some sim being most realistic have made a mistake. More mistakes comes from usually having zero experience from racing on circuit with comparable level cars and so many other things, that there really is no point in boasting any sim as most realistic, realism is good, there has to be enough of it, but it's totally meaningless for most players, no matter how much they run after realism, because if we analyze what those players really are after is nice feeling. But it has been that way for more than 20 years, surely I have been running after realism a lot too, but it really is not a thing, there are more important things that will make that feeling what realism seekers are after. iRacing has really great racing system, it really focuses on bringing feeling of racing and that it does well and as humans are so easily lead by their feelings and emotions, that is why they are making millions, they know where to focus to offer those experiences instead of spending 10 years to build numerical accuracy. To really understanding that is to create a wining product, as sales do matter. Enthusiasm/passion can be actually bad thing, even it is great source of feedback and really valuable strength, it can mislead the focus, it can make one think less clearly about what actually matters, that is very common.
You made a very good point about FFB vs Physics vs Realism. Very true and sometimes i forget and lose myself in the constant loop. For me personally the most important thing is how the car feels through my wheel. Don't care if the physics are not accurate. I dont expect it to be. Surely i dont want Forza in Raceroom. Forza is different beast and it serves different purpose.