Yes, the drummer is the leader or conductor and often has to be in sync with the soloist especially when starting a song or when they have to change tempo,rhythm etc,am sure you sometimes see that the soloists turn their back on the crowd and face the drummer especially when doing some complicated parts on a song for instance solo guitar signatures or what they call ''changement de frequence'' the drummer and soloist can make or break a serene.
Based on the shows i attend here in London, the guys criticise each other after the show but not to the point where they stop talking,they normally just discuss to say at that point on this song you were meant to do that but you did or the lyrics or notes you sang were wrong etc especially when playing other people's songs.