The attached pic shows what I found when I removed the rotting jambs from an exterior basement door in my 1951 brick house. The jambs were set into holes that lead under the basement concrete slab.

I have two questions: I think I need to fill-in those holes, don’t I? Or should I just let the new jambs “float” over them?

Second, the brick facade seems to purposely not align with the block walls just behind them, but they are different on the two sides. On one side, the brick extends about a half inch beyond the block, and on the other side, the block extends slightly beyond the brick. I’m not sure why this was done. But you can see how dollops of mortar were used to “shim” outward, to make up the difference. Should I leave those mortar dollops, or knock them off and replace with solid trim?