Delivery drivers are dependent on tips to make a livable wage, whether you agree with it or not. Tipping $0 is a low move.
That said, he shouldn't have thrown a fit over it.
His character confessed with respect to the priest right before his suicide mission. He didn't forsake God, as OP thinks, he embraced it at the end.
The rest is speculation.
No, there's always at least tiny bit of movement.
Now that I've watch this a few times over, it really just looks like the damned thing got hung up on something. There doesn't seem to be a strong enough breeze as the trees aren't swaying.