FWIW ping from mainland europe might be 90-150, but actual server latency is anywhere from 100-800, with keys not responding and skills either not going off or being super delayed.. business as usual.
But don't worry... ZOS is on it!! (for the last 3 years...)
No, not really. I play from Thailand and usually sit around 350. But it's not uncommon to go into 400s. Spikes can happen but it shouldn't sit at 600 or more.