I am also interested in how to exit. This is partially a security question because in the case the validator keys have been compromised it is possible for an attacker to cause slashing. A quick exit would be the only method to combat this.
at present, you have to do it manually via prysm command line… not sure on when this feature would be implemented… so for now, plan on staking… and staying with it…
As for your first two questions:
I can’t speak for the Advanced but I am running a Dappnode Extreme and it is pulling about 30watts running a bunch of packages.
Some people have been working on some monitoring tools with grafana and Prometheus. Also see ethdo/Attestant. Another easy way to monitor is just plug your validators into the beaconcha.in/dashboard and if they go down you can log into your Dappnode to resolve the issue.
the DMS Medalla package IS NOT READY YET!
But when it is, you will be able to use the same technique shown here for monitoring your validators: