Do this features work well?
Can it replace need for EM tool up to some frequencies?

I have tried but results are very poor. I don't recommend.

Is calibre better?

No, the same story.

What is then your recommendation?

Use EM tools for that purpose. Like HFSS, Momentum,...

But sometimes they are too slow for extraction.

I use EMX, because it is very fast. You can extract very big circuit using this tool.

I have red something about it but I didn't use.
There is not enough information available about EMX.
Website is very poor.

It is great tool it uses fastmultipl method for simulation.
It is 10x faster then others.

That is great. But what about accuracy?

It is not as accurace as hfss, but for parasitic extraction is very good.

I have read that it is integrated in calibre design flow.
If anyone has document for integration calibre and EMX, pleas share.

Please, share with me also.

They have build interface for cadence.
Using this you could simulate faster.