Have them answered in advance or lose to someone who does. People like surprises. I had a higher price and a reason to buy it. I was sure of my answers at every turn. I created the visualization of a successful outcome.
People buy with an outcome in mind.
Your job is not to know your product and your capabilities. It's to get the prospect to see the successful result of purchase. I knew the buying signals when they were offered. I assumed I had the sale from the start, and I asked for it when it was time to ask. Boy, I wish I knew the stock answer for that one.