The only real difference between being a soloist and an accompanist is that in the latter case you have to listen to sounds you aren't making yourself.
Yes, but I think we can be even more specific than sounds. It is not really the sounds, but the time.Thinking about it over the 19 days of this thread, we haven't emphasized time anywhere near enough. Playing together with a group is not about volume, expression, etc., but first and primarily about time. You have to listen with big ears! to the time. To the beat, to the change of the beat, to whether you are laying off the beat slightly in either direction, etc. You're lucky on piano, you don't need to include intonation. It is very common for experienced pianists (and especially organists) to become casual about time. I suspect they don't know it themselves, but the rest of us have come to expect keyboard players to be sloppy about time, unless they have experience playing in groups on another instrument. Count, subdivide, work with a metronome, play duets.
pianist should know each part as his own.That way the pianist can make adjustments on the fly during a rehearsal or a concert.Now if there is a conductor,the pianist must watch and follow the conductor at all times.Finally,a pianist must listen,hear and follow the other artist.
as accompanist, if needed we can cut some of the piano parts,especially if it is a transcription