Your questions about the interface and what its symbols means are answered in the Solo User Manual, pages 42-46. Have you read this yet? If not, PLEASE read the ENTIRE manual before even attempting to fly. See especially page 44-46, which explains how to tell the app exactly which GoPro model you have. Doing this activates the controls that you currently can't use. When all's set correctly, you remotely start and stop video recording by EITHER tapping the big red "Record Button" on the app screen (see page 44) OR you can use the secret method: press the gimbal tilt control paddle (behind the left side of the controller) *in* (you should feel it click).