Hi,
In trying to meet a friend who is arriving in CDG in a few days. I'll be coming in from downtown Paris to meet them. is it generally easy/frequent to get from the RER CDG1 station to Terminal 1? How does Terminal 1 look right now with the construction, and for any given airline, is the arrival exit point obvious and unique (i.e. when they exit immigration/baggage claim/customs, is there only one possible place they would be exiting?)

I ask because they don't have a mobile phone... Thanks...