This strongly depends on your traffic load, but since these are all fairly easy to change, I’d recommend you pick a size and see how well it performs. Aiming for between 3-10 app nodes to handle normal traffic is probably a good plan.
As long as the deployed images are built with our launcher script, this would be a supported configuration. This would correspond to our web_only sample config which they’ve already said they’re using.
We wouldn’t be able to help with the Kubernetes side of things though.