The strength in the mid section should improve as it is the central support structure, so it has to to keep the body stable.
As for the hernias, it depends what type. genetic/predisposed underlying weaknesses will 'always' lead to a hernia regardless. But weak abdominal structure can result from increasing IAP beyond what the abdominal wall can mitigate. I myself as a child had this happen to me from poor health and raised IAP from coughing (diaphram exerting more pressure than my abdominal wall could stand).