The Question and Answer section for A Christmas Carol is a great resource to ask questions, find answers, and discuss the novel.
I think this is to show that somebody actually did love Scrooge in his childhood. Scrooge knows what love is, he just represses it.
I think Scrooge was still working. He refused to see Marley until the workday was done.
GradeSaver has a detailed summary and analysis for Stave Four, readily available in its study guide for the unit.