I do not understand why the instructions for downloading those drivers have been taken off this site. They were included as part of the old instructions to set up the Arduino IDE.

This is a much easier question for me!

The current is calculated by emonLib, but it does not appear anywhere. It is calculated inside calcVI( … ), therefore it is available after the call to that. Just add:
Serial.print("Current 1 = ");Serial.println(ct1.Irms);
likewise for the other CTs. The best place to add this will be with the other print statements for power & voltage.

The clue is to look at emonlib.h
In there, you’ll see listed as “public”:
//Useful value variables double realPower, apparentPower, powerFactor, Vrms, Irms;
so all those are calculated and available. All you must do is print them to serial. If you want them in emonCMS, then it is a little harder - you must add them to the block of data transmitted and edit emonhub to expect the extra values at the other end.