@gemelen Thank you for your reply! Helpful as Im learning!
* Arm for control plane! Good one, already saving money!
* Node-groups, that seems not available to me as I use hetzner-k3s to deploy (not tf)
* Backup, good to note. On the todo list! 
* Rancher, I believe hetzner-k3s uses that, you mean to install the UI yourself?