Question

R’ Alter Yachness, the singer-songwriter of “Pharaoh in Pajamas in the Middle of the Night” 🎻, and also “A Lot of Clouds in the Sky” 🎸, and also “Fire Fire, Hot Hot,” and more, had challah separated and many children sang for his recovery.
In the end he passed away on Saturday night, and now there are those singing for the elevation of his soul.
 
My question:
Is singing for his recovery like saying Psalms for his recovery?
Why didn’t God save him and listen to the prayers-songs?
Is singing for the elevation of his soul like studying Mishnah for the elevation of his soul?
Do we have reliable knowledge of what this gives the dead?
 
I’d be happy if the Rabbi has answers even to only some of the questions.