+1 for Fargate and Lambda. If you do not like Fargate, you can also run containers in EC2 for a bit more control.
Nah, scaling will be hard. I came to realisation that I don’t want any clusters, let them manage it :)
We used to do this at my current job, but we've recently started transitioning to Kubernetes. There are certainly things I like a lot about it (specifically, the k9s CLI), but I definitely miss the simplicity of ECS/Fargate.