They can only strict from US investors for buying XRP same thing with bitstamp do to XRP. but major exchange will not totally delist it because they don't have any reason to do so ,unless they are from United States which need to also follow their countries regulations.
I don't know where they will make official announcement about the result of it ,. But hopefully they do it faster because as of today XRP is too much affected with that news.
Yes, they can. But it does not mean that the other exchanges will do the same as them because so far, XRP still has the potential to increase later, even if we do not know if that can happen or not. It still difficult to predict what will happen to XRP, and it is better to wait for more. I guess XRP will have the chance to increase again because this day, the green candle appears on that coin, so hopefully, that can be a moment for XRP to rise again.