Quote 4
Keller: I can afford another bag of potatoes. (1.238)
Keller threw the potatoes away because he thought they were garbage. This wastefulness provides an interesting contrast to his crime of saving machine parts (which actually were garbage) and selling them to the military.
Quote 5
Keller: Kid, walkin' down the street that day I was guilty as hell. Except I wasn't, and there was a court paper in my pocket to prove I wasn't, I and I walked… past… the porches. Result? Fourteen months later I had one of the best shops in the state again, a respected man again; bigger than ever. (1.446)
What matters to Keller is that he eventually restored his business to prosperity. Material success is the ultimate goal.
Quote 6
Keller: I don't know what you mean! You wanted money, so I made money. What must I be forgive? You wanted money, didn't you? (3.61)
Joe feels betrayed by Kate turning on him now. Like her neighbor Sue, she must have at some point encouraged him to make the family comfortable. Both Joe and Kate hide from their own responsibility in this matter.