'Wiring' has two meanings. We often use it to talk about the connections within a machine. It literally means the wires in a machine. Changing the way the wires connect can change the way the machine works. However, in this context we are talking about people, and so the idea of wiring withing a person is figurative not literal. It means the way the person thinks, functions, behaves, etc.
Q2. The subject is 'what makes a great manager'.