I'm guessing they mean paycheck by bills?

So they discount (lower) their employees' paychecks?

1. I think you're right about "labor grinder."

2. I think they follow the Trump method of not paying people who bill them for goods or services rendered, or claiming a "discount" and only paying part. Like him, they know the creditors usually can't afford to take it through court.

Labour grinder could mean his workers (labourers) are worked (grinded) to the bone.

These men should be running scared because Everett is secomds from dragging them out into the street and beating them to death.

Diabeetus

I suspect they were somewhat well known at the time. The caricatures have too much detail to be nobodies. Can't name them though, that'd be libelous.