Set Arena to start on boot-up. To do so, open the "Run" dialog box by pressing the Windows key + R. Type “shell:startup” (without the quotes) which will open the startup folder. Then drop a shortcut to Arena into that folder and next time you boot up Windows it will open Arena. Here is a link to help you through the process if you need more info: http://www.howtogeek.com/208224/how-to- ... ndows-8.1/
Set all your layers to "Trigger first clip when composition has loaded. This option will trigger the first clip in any layer that has clips loaded so for instance if you have no clips in L2C1 but one in L2C2 you want to put a dummy clip so that Arena triggers L2C1 rather than L2C2.
I use the [Solid Color] source to make dummy clips by setting the alpha to 0.
As a side tip, if you set the saturation and brightness to 0 on the dummy clip as well you can use that same clip to fade things out below it by controlling the alpha from 0 to 100.
As far as tuning Windows for permanent installs, you want to make sure you limit what starts on boot-up and you can check that our in the task manager. You'll find that menu under your task manager [Startup] tab.