What we have touched on here is the tip of an absolutely huge topic. And there are people here who know a great deal more than I do. I hope we hear from them.
There may be people out there who know more .etc.etc but you do have a knack of making the subject readable and useable by pianists who, out of the goodness of their hearts, have been cornered near the organ and given a hymn book and "see you next Sunday then".
Nothing can beat the opportunity to sit quietly in an empty church and fiddle with stops etc using just such information as you have provided above. On the whole, pianists who have been coerced into the job just want to do the best they can with a minimal amount of time on the organ itself. (Or at least this one does - if I had had the grand passion for the organ I would have become an organist 30+ years ago!!! )
Yes agree! I am planning to print out all this advice and take it to a hopefully very empty church. thanks again stopperman