APPLE IOS App store icon fix, and creating of HLS stream files

We have an application that we are getting ready to submit to the App store, and have a few areas that we need some help with. 1) We have an App store icon that is almost what we want, but it displays with a black background around it, when I put it into the Ipad or Iphone. I found a message that says it needs to be set to Opaque background and not transparent, but I don't know how to set this. 2) We have several mp4 files that we created an HLS stream for and they work properly in our application, but we need additional HLS streams for the APP store approval, including one with Audio only, and a still image. We aren't sure how to create this. (If you haven't used the Apple stream tools, please don't apply. We want to use the apple HLS tool set, and validator tools to help smooth the approval process for the APP store. You will need to use Teamviewer to connect into the system to work on the HLS files. If you have successfully submitted an app to the App store, that will certainly be helpful, as you may know of some others issues we haven't addressed.