Deep Sleep vs update_interval basic question

I’m a newbie to ESPHome (well ESP32 really) and need to ask some verrrrry basic questions.

I added an “update_interval: 900s” to a thermistor report to save battery use.

  1. Am I right in assuming if I want to use deep sleep, this should be removed because the reporting interval will not necessarily match the wake-up period?

  2. I read that using MQTT is the best way to ensure communication when using deep-sleep. Is that still the case. (I gather the alternative is the API and this can be problematic… any readings suggested on that?)