The light and switches are easy so we should focus on the AV side.
Someone here may have a better way to do this, but I'm more a meat and potatoes guy so I will give you my approach.
We use and recommend Logitech Harmony/Elite Remotes/Hubs to integrate your AV into HE. Once you have the Logitech setup to control the TV/Chromecast/Shield/Amp you can the program those same controls into HE.
I use the fabulous driver by @ogiewon Harmony Hub Driver to program a "morning" button for my wife on our Lurton keypad.
If you need additional details on the setup feel free to ask
