Is it necessary to be an expert in the industry that a project manager works in?
In fact, no. It does help, though.
Is there a great project management book?
Tons of it. But the best advice I can give is to work on projects.
What is the biggest challenge in project management?
People. They will not tell you the truth, they may tell the truth that they believe in but they don’t really know what they are talking about or they have their own agenda. You need to master your skills when it comes to dealing with people.
Is a Gantt Chart the best project plan?
A Gantt Chart is not a project plan. It is just a way of scheduling the work to be done.