I get regular emails from people asking questions about songs and copyright. I’m certainly no expert, but I have written a few articles that you might find helpful.
I’ve also just discovered something called The Code of Fair Practice which (in the UK only) allows people in certain circumstances to get around copyright issues.
Many choir leaders end up feeling like song factories because we feel that our singers crave novelty. If we don’t keep giving them new things, they might leave.
Actually most singers in a choir welcome singing the old, familiar songs and find it hard learning new stuff all the time. It’s important to find the balance.