Some questions after getting familiar with HA

Hei Guys, after being familiar with HA and having running some sensors and automations successfully there are some questions that came across.

  1. I set up Duck DNS Addon and external URL. In the tutorial I followed
    the option


was suggested. This seams to be deprecated but still works successfully. homeassistant:8123/ doesn’t work anymore. Do I have to put the internal_url and external_url options? I heard of a mistake that may lock me out of HA and now I’m in fear of provocating this.

  1. I got some sonoff sensors running with tasmota. I’m updating the values every 60 seconds? Is that OK or should I use greater values because of MQTT-Traffic (at the moment I got 9 sensors but the number will grow if everthing works fine).

  2. I got some automations that are triggered by the sensors. Unfortunately It happened one time that a sensor did not send values for about 3 hours. Is there an option to trigger an automation, when a sensor is not available, e.g. not sending for 5 minutes? (or something similar)

  3. Is it sufficient to backup the snapshots or should I make an Image of the SD-Card? (I would like to avoid that because of the memory used).

5.Are there jobs or scripts to backup sensor history to googleCloud or similar?

Hope you guys have some ideas.

can anyone please help me out at least with one question ?
regards Manuel