I have not. I will have a read, thanks.

Try Inoreader. I’m using free plan but paid one gives a lot of features you could find interesting.

I’ve been using Inoreader for few years and there is no single thing I could complain about. It’s good enough that I’m considering buying a subscription.

web01, web02, … db01, db02, … api01, api02, …

You get the idea.

Both. Start with docker as there’s a buttload of tutorials. Once you’re familiar with it jump to podman. Learn the differences, use both for a while and decide what suits you best.

Syncthing

Obaidian + Syncthing will do the trick.

I wouldn’t expect anything else. Kill it and start again. If it still misbehaving, kill it again and check what’s listening on problematic ports.

Run docker ps and kill all running sonarr/radarr containers.