I have a whole home audio system and a receiver which controls it. Would I be able to create a tile which when selected would open my Onkyo receiver app?
Also, would I be able to create a tile which would have all my switches and devices per room?
Most people will probably recommend you use fully kiosk for your tablet. if you do, You can use this to open any installed app on your tablet from the browser:
AND
As for your other question, it depends on how much effort you are willing to put into it. Almost everything is possible. I created an interactive floor plan of my apartment that shows most of my devices and let’s me toggle them on or off.
It also looks like there is some basic integration for Onkyo receivers with most hubs. In that case you would be able to have some basic control over the receiver from the dashboard directly.