2006 Sportsman 700 Issues

New to the forum.
My 2006 Sportsman 700 is New to me.
I have a list questions regarding some issues I am having.

1. When I turn on the key, the Check Engine is displayed. Once I start it. Check Engine not displayed. Is this normal?

2. What does flashing Battery symbol indicate? (If lights are on, the Speedometer needle also flashes)

3. If I throttle down quickly, I hear a ‘clicking’ sound as the quad decelerates. Same clicking if the throttle is at idle, and I am going down a hill.

4. What is a ‘wrench’ displayed indicate?

Any assistance would be greatly appreciated
Thanks.