I am doing the CMA festival and am purchasing the parking pass. My question is, is the festival activities and the main shows all at the stadium or will I need parking somewhere else also?

You can park at stadium ... and walk to everything ... it's all downtown around Broadway and 2nd

Last year all of the events and parking were at the stadium. I assume this year will be the same.

For that you would have to call the stadium ahead of time, they will tell you which events the stadium will host.

What time does open in the morning

Park across the river and avoid most of the traffic getting out of the stadium.