The preferred order will not change but rather the next active device will. In your example, bigip-test-1 will become active and bigip-test-2 will be the next active device. Also note, that you have auto failback enabled. The traffic-group-2 will automatically failover back to bigip-test-2 after 60 seconds of being available.
That is correct.
8. If you configured the Failover Methods setting with a value of Failover using Preferred Device List and then Load Aware, then configure the following settings. Otherwise, skip this step.